-10.47% is the change from 191 to 171
Calculation steps:
[( 171 - 191 ) ÷ 191] x 100 = -10.47%
Formula
Percentage change = [(171 - 191) / 191] x 100
Subtract the new number by the original number
171 - 191 = -20
-20 ÷ 191 = -0.10471204188481675
-0.10471204188481675 x 100 = -10.47%