Vertical analysis (common-size) percentages for Palau Company’s sales revenue, cost of goods sold, and expenses are listed here.

Vertical Analysis 2017 2016 2015 LO15 Sales revenue 100.0% 100.0% 100.0%
Cost of goods sold 60.5 62.9 64.8 Expenses 26.0 26.6 27.5 Did Palau’s net income as a percent of sales increase, decrease, or remain unchanged over the 3-year period? Provide numerical support for your answer.