-6.05% is the change from 991 to 931
Calculation steps:
[( 931 - 991 ) ÷ 991] x 100 = -6.05%
Formula
Percentage change = [(931 - 991) / 991] x 100
Subtract the new number by the original number
931 - 991 = -60
-60 ÷ 991 = -0.060544904137235116
-0.060544904137235116 x 100 = -6.05%