-98.37% is the change from 921 to 15
Calculation steps:
[( 15 - 921 ) ÷ 921] x 100 = -98.37%
Formula
Percentage change = [(15 - 921) / 921] x 100
Subtract the new number by the original number
15 - 921 = -906
-906 ÷ 921 = -0.9837133550488599
-0.9837133550488599 x 100 = -98.37%