-68.14% is the change from 521 to 166
Calculation steps:
[( 166 - 521 ) ÷ 521] x 100 = -68.14%
Formula
Percentage change = [(166 - 521) / 521] x 100
Subtract the new number by the original number
166 - 521 = -355
-355 ÷ 521 = -0.6813819577735125
-0.6813819577735125 x 100 = -68.14%