condition mean min max ZT0-3 14.649999999999999 14.649999999999999 14.649999999999999 ZT4-7 9.0 9.0 9.0 ZT8-11 23.65 23.65 23.65 ZT12-15 3.4000000000000004 3.4000000000000004 3.4000000000000004 ZT16-19 12.799999999999999 12.799999999999999 12.799999999999999 ZT20-23 12.5 12.5 12.5