-37.52% is the change from 509 to 318
Calculation steps:
[( 318 - 509 ) ÷ 509] x 100 = -37.52%
Formula
Percentage change = [(318 - 509) / 509] x 100
Subtract the new number by the original number
318 - 509 = -191
-191 ÷ 509 = -0.37524557956778
-0.37524557956778 x 100 = -37.52%