99.5% is the change from 201 to 401
Calculation steps:
[( 401 - 201 ) ÷ 201] x 100 = 99.5%
Formula
Percentage change = [(401 - 201) / 201] x 100
Subtract the new number by the original number
401 - 201 = 200
200 ÷ 201 = 0.9950248756218906
0.9950248756218906 x 100 = 99.5%