Analyze the financial data of General Motors for the years 2019, 2020, and 2021:

	2019	2020	2021
Revenue	$137,237	$122,485	$127,004
Cost of Goods Sold	$114,109	$102,023	$106,473
Gross Profit	$23,128	$20,462	$20,531
Operating Expenses	$13,736	$13,257	$13,793
Operating Income	$9,392	$7,205	$6,738
Net Income	$6,732	$5,922	$5,285

	2019	2020	2021
Total Assets	$228,037	$235,194	$244,862
Total Liabilities	$166,389	$172,715	$178,491
Shareholders' Equity	$61,648	$62,479	$66,371

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 trend of General Motors.