FML Corporation has $10$ million ordinary shares outstanding that are currently priced at $$17$ each and have a beta of $0\mathrm{.}70.$ The company has $1,000,000$ preference shares trading at $$12$ each. The return on the stock market is $18\%$ p$.$a$.,$ the risk$-$free return is $1\%$ p$.$a$.,$ and the company tax rate is $30\%.$ Eight years ago FML Corporation issued bonds with a total face value of $$12$ million. One bond has a face value of $$500,000.$ The bonds have a coupon rate of $10\%$ p$.$a$.$ and coupons are paid annually. The bonds mature in six years from today. The bonds currently yield $9\%$ p$.$a$.$

What proportion of the firm's capital structure is debt?