-2.54% is the change from 631 to 615
Calculation steps:
[( 615 - 631 ) ÷ 631] x 100 = -2.54%
Formula
Percentage change = [(615 - 631) / 631] x 100
Subtract the new number by the original number
615 - 631 = -16
-16 ÷ 631 = -0.025356576862123614
-0.025356576862123614 x 100 = -2.54%