-2.67% is the change from 637 to 620
Calculation steps:
[( 620 - 637 ) ÷ 637] x 100 = -2.67%
Formula
Percentage change = [(620 - 637) / 637] x 100
Subtract the new number by the original number
620 - 637 = -17
-17 ÷ 637 = -0.026687598116169546
-0.026687598116169546 x 100 = -2.67%