-83.25% is the change from 991 to 166
Calculation steps:
[( 166 - 991 ) ÷ 991] x 100 = -83.25%
Formula
Percentage change = [(166 - 991) / 991] x 100
Subtract the new number by the original number
166 - 991 = -825
-825 ÷ 991 = -0.8324924318869829
-0.8324924318869829 x 100 = -83.25%