2.57% is the change from 623 to 639
Calculation steps:
[( 639 - 623 ) ÷ 623] x 100 = 2.57%
Formula
Percentage change = [(639 - 623) / 623] x 100
Subtract the new number by the original number
639 - 623 = 16
16 ÷ 623 = 0.025682182985553772
0.025682182985553772 x 100 = 2.57%