-21.33% is the change from 661 to 520
Calculation steps:
[( 520 - 661 ) ÷ 661] x 100 = -21.33%
Formula
Percentage change = [(520 - 661) / 661] x 100
Subtract the new number by the original number
520 - 661 = -141
-141 ÷ 661 = -0.21331316187594554
-0.21331316187594554 x 100 = -21.33%