-85.11% is the change from 611 to 91
Calculation steps:
[( 91 - 611 ) ÷ 611] x 100 = -85.11%
Formula
Percentage change = [(91 - 611) / 611] x 100
Subtract the new number by the original number
91 - 611 = -520
-520 ÷ 611 = -0.851063829787234
-0.851063829787234 x 100 = -85.11%