2.4% is the change from 624 to 639
Calculation steps:
[( 639 - 624 ) ÷ 624] x 100 = 2.4%
Formula
Percentage change = [(639 - 624) / 624] x 100
Subtract the new number by the original number
639 - 624 = 15
15 ÷ 624 = 0.02403846153846154
0.02403846153846154 x 100 = 2.4%