An investor has an investment that has produced the following returns: Year $1$: $10\%,$ Year $2$ : $5\%,$ Year $3$: $-7\%,$ Year $4$: $-3\%,$ Year $5$:$12\%.$ Calculate the arithmetic mean return on this investment.

$6\mathrm{.}75$

$17\mathrm{.}00$

$3\mathrm{.}40$

$8\mathrm{.}50$