-3.32% is the change from 331 to 320
Calculation steps:
[( 320 - 331 ) ÷ 331] x 100 = -3.32%
Formula
Percentage change = [(320 - 331) / 331] x 100
Subtract the new number by the original number
320 - 331 = -11
-11 ÷ 331 = -0.03323262839879154
-0.03323262839879154 x 100 = -3.32%