-3.34% is the change from 539 to 521
Calculation steps:
[( 521 - 539 ) ÷ 539] x 100 = -3.34%
Formula
Percentage change = [(521 - 539) / 539] x 100
Subtract the new number by the original number
521 - 539 = -18
-18 ÷ 539 = -0.03339517625231911
-0.03339517625231911 x 100 = -3.34%