3.12% is the change from 321 to 331
Calculation steps:
[( 331 - 321 ) ÷ 321] x 100 = 3.12%
Formula
Percentage change = [(331 - 321) / 321] x 100
Subtract the new number by the original number
331 - 321 = 10
10 ÷ 321 = 0.03115264797507788
0.03115264797507788 x 100 = 3.12%