Using the following financial data of Chevron Corporation for the years 2018, 2019, and 2020, perform the required analysis:

	2018	2019	2020
Revenue	$158,902	$146,516	$94,703
Cost of Revenue	$88,286	$83,641	$69,950
Gross Profit	$70,616	$62,875	$24,753
Operating Expenses	$40,878	$38,963	$33,446
Operating Income	$29,738	$23,912	-$8,693
Net Income	$14,824	$2,924	-$5,543

	2018	2019	2020
Total Assets	$253,863	$237,468	$239,755
Total Liabilities	$101,500	$93,130	$111,831
Shareholders' Equity	$152,363	$144,338	$127,924

Requirements:

1. Calculate the gross profit margin for each year.
2. Determine the operating profit margin for each year.
3. Calculate the net profit margin for each year.
4. Compute the return on assets (ROA) for each year.
5. Compute the return on equity (ROE) for each year.
6. Discuss the financial performance and trend of Chevron Corporation over these three years.