-99.7% is the change from 660 to 2
Calculation steps:
[( 2 - 660 ) ÷ 660] x 100 = -99.7%
Formula
Percentage change = [(2 - 660) / 660] x 100
Subtract the new number by the original number
2 - 660 = -658
-658 ÷ 660 = -0.996969696969697
-0.996969696969697 x 100 = -99.7%