A retail store had sales of $33,500 in April and $68,500 in May. The store employs nine fulltime workers who work a 40 - hour week. In April the store also had six part-time workers at 10 hours per week, and in May the store had eleven part-timers at 15 hours per week (assume four weeks in each month). Required: Using sales dollars as the measure of output, what is the percentage change in productivity from April to May? (Round your answer to 2 decimal places. Omit the "%" sign in your response.)