Executives at Golden Baking Co$.$ have been doing competitor research on their rival, Purity Grahams. The team at Golden Baking has determined that, last year, Purity Grahams had market share of $13\mathrm{.}3\%$ and earned $39\mathrm{.}3\%$ share of requirements from Purity customers, who had a usage index of $106\mathrm{.}5\%.$Find PENETRATION SHARE for Purity Grahams, given these numbers. $($Report your answer as a percent, and round your answer to the nearest tenth of a percent. $$Report $27\mathrm{.}5\%,$ for example, as $"27\mathrm{.}5".)$