-3.02% is the change from 331 to 321
Calculation steps:
[( 321 - 331 ) ÷ 331] x 100 = -3.02%
Formula
Percentage change = [(321 - 331) / 331] x 100
Subtract the new number by the original number
321 - 331 = -10
-10 ÷ 331 = -0.030211480362537766
-0.030211480362537766 x 100 = -3.02%