Your assignment is 100+x percent <-> y = 100 * 1.18^(x-1) points for x=1..100. So y points corresponds to log(y/100) / log(1.18) + 101 percent.

For example, log(249746062.72 / 100) = 14.7307, log(1.18) = 0.1655, and the ratio is 89, giving 190 percent.