My name is Sakai of Idemitsu. I would like to go over our financial results using our presentation materials. Page two provides a summary of our financial results for fiscal year 2020. Segment income increased to JPY 100.3 billion, supported by positive inventory impact and improved time lag in the petroleum segment. Valuation losses on loans to NSRP were reported as extraordinary losses. Net income increased by JPY 57.9 billion year-on-year to JPY 34.9 billion. As shown, year-end dividends were in line with the previous announcement at JPY 60 per share for an annual total of JPY 120 per share. Earnings forecasts for fiscal year 2021 are shown on page three. We forecast segment income of JPY 140 billion and net income of JPY 85 billion with a recovery in resource prices and reduced impact from the COVID-19 pandemic.
With respect to shareholder returns, we plan to achieve a cumulative total payout ratio of at least 50% over the three years ending in fiscal year 2022, with forecasted dividends of JPY 120 per share. Page four summarizes our key topics for fiscal year 2020. First, the COVID-19 pandemic impacted petroleum and all other operations throughout the year. Nghi Son Refinery in Vietnam continues to operate steadily. Earnings were generally in line with previous forecasts. In addition, our exposure to NSRP was reduced after recording valuation losses on long-term loans of JPY 18.1 billion. In order to allow for a more rapid and flexible shareholder returns policy, a plan to reclassify a portion of legal capital surplus to other capital surplus was approved by the board and will be presented as an agenda item at the annual shareholders' meeting to be held next month.
Graphs showing trends in crude oil prices, coal prices, and foreign exchange rates are shown on page five. Page six shows an overview of our financial results. While inventory impact improved significantly, equity losses increased, of which about half was associated with NSRP. Major extraordinary losses included valuation losses on loans to NSRP and impairment losses relating to resources. As a result, net sales decreased in fiscal year 2020, while net income increased. I would now like to go over major points relating to each segment. Page nine summarizes the petroleum business. Sales volume of the four core products is as shown in the graph on your left. Sales volume basically remained unchanged in the fourth quarter on a year-on-year basis, while sales volume for the entire fiscal year was 94.6% of the previous fiscal year.
The graph on your right illustrates refining margins for the four core products, which increased by JPY 2.4 per liter year-on-year. A JPY 82 billion increase was achieved due to time lag at a time of increasing crude oil prices. Synergies, reduced fuel cost, and other factors led to a JPY 50.8 billion increase. This figure is composed of JPY +13.8 billion from synergies, JPY +10.8 billion from increased income at affiliates, JPY +18 billion from reduced fuel costs, JPY +21.7 billion from reduced overhead costs, and JPY +16 billion from byproducts, offset by JPY -8.4 billion for equity losses and JPY -19 billion from a decrease in jet fuel volume. Next is the basic chemicals segment. Profits decreased due to reduced margins, mainly resulting from the COVID-19 pandemic. Profits in the functional materials segment decreased by JPY 15.4 billion year-on-year, mainly due to reduced lubricant oil sales due to COVID-19.
The power and renewable energy segment reported a JPY 16.8 billion decrease as a result of a soaring JEPX market. Profits in the solar business also decreased. Page 11 shows the performance of our oil exploration and production segment. The bar graph shows production volume, while the line graph shows trends in Brent crude oil prices. While production volume increased year-on-year, crude oil prices fell sharply. Segment income decreased by JPY 11 billion as a result. The coal business is summarized on the right side, with the bar graph showing production volume and the line graph showing Australian coal spot price trends. Income from coal decreased by JPY 26 billion as both production volume and prices decreased on a year-on-year basis. Our balance sheet is summarized on page 12. Total assets shown on the lower left increased by JPY 67.5 billion year-on-year to JPY 3.9544 trillion.
Shareholders' equity is shown near the middle of the right column. While net income was JPY 34.9 billion, shareholders' equity increased by JPY 0.9 billion due to dividend payments, et cetera. Interest-bearing debt and equity ratio are as shown on the lower right. Page 13 is a summary of our cash flows. Cash outflows from investing activities exceeded JPY 100 billion, with maintenance and renewals in the petroleum business and investments in the resources and U.S. solar businesses. Operating cash flows amounted to JPY 170 billion. Cash outflows from financing activities included repayment of borrowings and dividend payments. As a result, the final cash balance was JPY 131 billion. Key ESG topics are listed on page 14. New initiatives such as the sustainable procurement guideline and human rights due diligence were launched, as stated in the middle row. Next, I would like to go over our forecast for fiscal year 2021.
Page 15 covers two key topics. The first is the impact of COVID-19. The chart shows sales volume forecasts for the four core petroleum products and jet fuel. Despite uncertainties surrounding future circumstances, we assume a gradual trend towards recovery. Nghi Son in Vietnam continues to operate steadily. Singapore product markets are also gradually improving. We forecast an increase in earnings from Nghi Son Refinery in fiscal year 2021, mainly from its overhead cost reduction efforts. In addition, the fiscal year 2020 valuation losses mentioned earlier will be offset by NSRP equity losses in fiscal year 2021. Page 16 provides an overview of our forecasts. Our assumptions for crude oil prices, coal prices, and foreign exchange rates are as shown here. Our segment and net income forecasts are JPY 140 billion and JPY 85 billion, respectively. Equity income will improve significantly due to the improvement at NSRP.
Extraordinary losses will improve significantly due to the valuation losses on loans to NSRP reported in fiscal year 2020. As a result, we forecast an increase in both net sales and net income in fiscal year 2021. I would like to explain our forecast for each segment beginning on page 19. In the petroleum segment, we forecast a gradual recovery in sales volume by about 500,000 kL for the four core products. As a positive impact from time lag was reported in the previous fiscal year, margins are forecasted to decrease. As a result, we forecast a JPY 10.7 billion year-on-year decrease in operating income. We forecast a JPY 6.6 billion year-on-year increase from basic chemicals, mainly due to margin improvements for paraxylene, et cetera. The JPY 3 billion increase forecasted in functional materials mainly comes from the expected recovery in lubricant sales. Please turn to page 20.
We forecast an JPY 11.3 billion increase in the power and renewable energy segment. Profits are forecasted to increase due to reversal of the sharp increase in the JEPX market observed during the previous fiscal year. Income from oil exploration production is expected to increase as a result of added production volumes from Vietnamese gas fields launched last November. Brent prices are also expected to increase, leading to a total year-on-year increase of JPY 26.2 billion . Coal sales volume is expected to increase due to recovery and production after unfavorable weather conditions in the previous year. Thermal coal prices are also increasing. As a result, we forecast an increase of JPY 9 billion year-on-year from the coal business. Page 21 summarizes investments made in fiscal year 2020 and our forecast for fiscal year 2021. Maintenance and renewal investments will increase, mainly in relation to Chiba and Aichi SDM.
Strategic investments include mega solar for power and renewable energy, a new lubricant plant, overseas investments in the functional chemicals business, and lithium-related investments. In the resources segment, JPY 38 billion will be used for strategic investments in Vietnamese gas fields, et cetera. Finally, forecasts relating to our financial position are summarized on page 22. For your reference, our forecasted balance sheet and cash balance have been calculated based on our performance forecasts, expected investments, and shareholder returns policies for fiscal year 2021 explained thus far. That concludes my presentation.