Shinoda Corp. has $8\mathrm{.}47$ percent coupon bonds making annual payments with a YTM of $6\mathrm{.}26$ percent. The current yield on these bonds is $6\mathrm{.}78$ percent.

How many years do these bonds have left until they mature?

Do not round intermediate calculations and round your final answer to $2$ decimal places. $($e$.$g$.,32\mathrm{.}16).$