fixes lowest performing student query
fixes lowest performing student query

fixes lowest performing student query to make it more performant and never show students with zero

empirical-org/Empirical-Core,empirical-org/Empirical-Core,empirical-org/Empirical-Core,empirical-org/Empirical-Core,empirical-org/Empirical-Core,empirical-org/Empirical-Core,empirical-org/Empirical-Core