-18.01% is the change from 311 to 255
Calculation steps:
[( 255 - 311 ) ÷ 311] x 100 = -18.01%
Formula
Percentage change = [(255 - 311) / 311] x 100
Subtract the new number by the original number
255 - 311 = -56
-56 ÷ 311 = -0.18006430868167203
-0.18006430868167203 x 100 = -18.01%