Double your money$-$Rule of $72.$ Approximately how long will it take to double your money if you get an annual return of $4\mathrm{.}9\%,7\mathrm{.}6\%,$ or $10\mathrm{.}2\%$ on your investment?

Approximately how long will it take to double your money if you get a $4\mathrm{.}9\%$ annual return on your investment?

$$ years $($Round to two decimal places.$)$