-96.1% is the change from 539 to 21
Calculation steps:
[( 21 - 539 ) ÷ 539] x 100 = -96.1%
Formula
Percentage change = [(21 - 539) / 539] x 100
Subtract the new number by the original number
21 - 539 = -518
-518 ÷ 539 = -0.961038961038961
-0.961038961038961 x 100 = -96.1%