-3.13% is the change from 991 to 960
Calculation steps:
[( 960 - 991 ) ÷ 991] x 100 = -3.13%
Formula
Percentage change = [(960 - 991) / 991] x 100
Subtract the new number by the original number
960 - 991 = -31
-31 ÷ 991 = -0.03128153380423814
-0.03128153380423814 x 100 = -3.13%