condition mean min max ZT0-3 20.936733333333333 19.009 22.02345 ZT4-7 17.9906 17.9906 17.9906 ZT8-11 16.0844 16.0844 16.0844 ZT12-15 16.56105 14.970600000000001 18.1515 ZT16-19 17.2951 17.2951 17.2951 ZT20-23 16.631999999999998 16.631999999999998 16.631999999999998