Media Productions Inc. reports the following financial results for the past three years.

Description	2021	2020	2019
Total Revenue	$15,000,000	$14,500,000	$14,000,000
Cost of Revenue	$9,000,000	$8,700,000	$8,400,000
Gross Profit	$6,000,000	$5,800,000	$5,600,000
Operating Expenses	$3,000,000	$2,900,000	$2,800,000
Operating Income	$3,000,000	$2,900,000	$2,800,000
Other Income	$600,000	$580,000	$560,000
Earnings Before Tax	$3,600,000	$3,480,000	$3,360,000
Tax Expense	$720,000	$696,000	$672,000
Net Income	$2,880,000	$2,784,000	$2,688,000

Requirements:

1. Prepare a common-size income statement for each year.
2. Calculate the Operating Expense Ratio for each year.
3. Determine the Net Profit Margin for each year.
4. Discuss the trend in profitability over the three years.