condition mean min max ZT0-3 15.963996 15.963996 15.963996 ZT4-7 12.7967415 12.7967415 12.7967415 ZT8-11 13.673308500000001 13.673308500000001 13.673308500000001 ZT12-15 14.933789999999998 14.933789999999998 14.933789999999998 ZT16-19 19.378839499999998 19.378839499999998 19.378839499999998 ZT20-23 25.529226 25.529226 25.529226