31.1% is the change from 164 to 215
Calculation steps:
[( 215 - 164 ) ÷ 164] x 100 = 31.1%
Formula
Percentage change = [(215 - 164) / 164] x 100
Subtract the new number by the original number
215 - 164 = 51
51 ÷ 164 = 0.31097560975609756
0.31097560975609756 x 100 = 31.1%