Shaka's Sandwiches operates on a busy street downtown, and only serves lunch, and only Monday through Friday. Within its narrowly defined market, Shaka's Sandwiches believes that it gets $39\mathrm{.}8\%$ of its customers' workday lunch business. Its customers are a big lunch$-$eating crown with a usage index of about $145\mathrm{.}6\%.$ Unfortunately, only a small slice of the street's lunchtime customers visit Shaka's Sandwiches$--$the shop's penetration share is only $10\mathrm{.}7\%.$ Calculate market share for Shaka's Sandwiches. Report your answer as a percent. Round to the nearest tenth of a percent. Report $25\mathrm{.}5\%,$ for example, as $"25\mathrm{.}5".$