-32.59% is the change from 991 to 668
Calculation steps:
[( 668 - 991 ) ÷ 991] x 100 = -32.59%
Formula
Percentage change = [(668 - 991) / 991] x 100
Subtract the new number by the original number
668 - 991 = -323
-323 ÷ 991 = -0.32593340060544906
-0.32593340060544906 x 100 = -32.59%