-83.96% is the change from 991 to 159
Calculation steps:
[( 159 - 991 ) ÷ 991] x 100 = -83.96%
Formula
Percentage change = [(159 - 991) / 991] x 100
Subtract the new number by the original number
159 - 991 = -832
-832 ÷ 991 = -0.8395560040363269
-0.8395560040363269 x 100 = -83.96%