condition mean min max ZT0-3 13.1 13.1 13.1 ZT4-7 9.6 9.6 9.6 ZT8-11 20.849999999999998 20.849999999999998 20.849999999999998 ZT12-15 27.85 27.85 27.85 ZT16-19 2.8499999999999996 2.8499999999999996 2.8499999999999996 ZT20-23 3.3 3.3 3.3