Refer to the following income statements of AT&T Inc. for the fiscal years 2022 and 2021.

AT&T Inc.	2022	2021
Sales	$168,864	$167,821
Cost of Goods Sold	$75,435	$73,678
Gross Profit	$93,429	$94,143
Operating Expenses	$45,763	$45,098
Net Income	$29,556	$27,827

Requirements:

1. Calculate the gross profit margin for each year.
2. Calculate the operating profit margin for each year.
3. Compute the net profit margin for each year.
4. Analyze the profitability trends of AT&T Inc. from 2021 to 2022.