$(1$ point$)$ You might recall that Silicon Valley Bank $($SVB$)$ failed during the spring of $2023,$ primarily due to losses in its hold$-$to$-$maturity $($HTM$)$ portfolio. Let's use the concept of duration to shed some light on what happened. On December $31,2021,$ the fair value of the securities in SVB$\text{'}$s HTM portfolio was approximately $$97$ billion. During $2022,$ the $10-$year constant maturity treasury $($CMT$)$ yield, which is a reasonable proxy for the rate to which the HTM portfolio was exposed, increased from $1\mathrm{.}49\%$ to $3\mathrm{.}79\%,$ or by $2\mathrm{.}3\%.$ During $2022,$ SVB$\text{'}$s HTM portfolio experienced losses of about $$14$ billion. Based on these numbers, what was the approximate $($modified$)$ duration of SVB$\text{'}$s HTM portfolio?