-97.8% is the change from 91 to 2
Calculation steps:
[( 2 - 91 ) ÷ 91] x 100 = -97.8%
Formula
Percentage change = [(2 - 91) / 91] x 100
Subtract the new number by the original number
2 - 91 = -89
-89 ÷ 91 = -0.978021978021978
-0.978021978021978 x 100 = -97.8%