-90.96% is the change from 166 to 15
Calculation steps:
[( 15 - 166 ) ÷ 166] x 100 = -90.96%
Formula
Percentage change = [(15 - 166) / 166] x 100
Subtract the new number by the original number
15 - 166 = -151
-151 ÷ 166 = -0.9096385542168675
-0.9096385542168675 x 100 = -90.96%