Software Solutions Inc. reports the following financial results for the past three years.

Description	2021	2020	2019
Total Revenue	$4,000,000	$3,800,000	$3,600,000
Cost of Revenue	$2,400,000	$2,280,000	$2,160,000
Gross Profit	$1,600,000	$1,520,000	$1,440,000
Research and Development	$800,000	$760,000	$720,000
Selling, General, and Admin	$400,000	$380,000	$360,000
Total Operating Expenses	$1,200,000	$1,140,000	$1,080,000
Operating Income	$400,000	$380,000	$360,000
Other Income	$80,000	$76,000	$72,000
Earnings Before Tax	$480,000	$456,000	$432,000
Tax Expense	$96,000	$91,200	$86,400
Net Income	$384,000	$364,800	$345,600

Requirements:

1. Calculate the Gross Profit Ratio for each year.
2. Determine the R&D Expense Ratio for each year.
3. Compute the Net Profit Margin for each year.
4. Analyze the company's investment in R&D over the three years.