Vertical analysis (common-size) percentages for Vallejo Company's sales, cost of goods sold, and expenses are listed here.
![137_Vertical analysis.PNG](https://secure.tutorsglobe.com/CMSImages/137_Vertical%20analysis.PNG)
Did Vallejo's net income as a percent of sales increase, decrease, or remain unchanged over the 3-year period? Provide numerical support for your answer.