condition mean min max ZT0-3 8.27989 8.27989 8.27989 ZT4-7 7.3749139999999995 7.3749139999999995 7.3749139999999995 ZT8-11 8.026881 8.026881 8.026881 ZT12-15 8.746588500000001 8.746588500000001 8.746588500000001 ZT16-19 9.4268735 9.4268735 9.4268735 ZT20-23 9.3578925 9.3578925 9.3578925