condition mean min max ZT0-3 6.528796666666667 3.18444 8.21405 ZT4-7 4.838839999999999 4.838839999999999 4.838839999999999 ZT8-11 6.458975000000001 6.458975000000001 6.458975000000001 ZT12-15 6.93818 6.326715 7.549645 ZT16-19 6.8053799999999995 6.8053799999999995 6.8053799999999995 ZT20-23 7.93545 7.93545 7.93545