3.44% is the change from 639 to 661
Calculation steps:
[( 661 - 639 ) ÷ 639] x 100 = 3.44%
Formula
Percentage change = [(661 - 639) / 639] x 100
Subtract the new number by the original number
661 - 639 = 22
22 ÷ 639 = 0.03442879499217527
0.03442879499217527 x 100 = 3.44%