-97.5% is the change from 639 to 16
Calculation steps:
[( 16 - 639 ) ÷ 639] x 100 = -97.5%
Formula
Percentage change = [(16 - 639) / 639] x 100
Subtract the new number by the original number
16 - 639 = -623
-623 ÷ 639 = -0.974960876369327
-0.974960876369327 x 100 = -97.5%