-3.45% is the change from 637 to 615
Calculation steps:
[( 615 - 637 ) ÷ 637] x 100 = -3.45%
Formula
Percentage change = [(615 - 637) / 637] x 100
Subtract the new number by the original number
615 - 637 = -22
-22 ÷ 637 = -0.03453689167974882
-0.03453689167974882 x 100 = -3.45%