-17.96% is the change from 991 to 813
Calculation steps:
[( 813 - 991 ) ÷ 991] x 100 = -17.96%
Formula
Percentage change = [(813 - 991) / 991] x 100
Subtract the new number by the original number
813 - 991 = -178
-178 ÷ 991 = -0.17961654894046417
-0.17961654894046417 x 100 = -17.96%