condition mean min max ZT0-3 7.75 7.75 7.75 ZT4-7 2.3 2.3 2.3 ZT8-11 17.4 17.4 17.4 ZT12-15 5.2 5.2 5.2 ZT16-19 24.450000000000003 24.450000000000003 24.450000000000003 ZT20-23 19.849999999999998 19.849999999999998 19.849999999999998