condition mean min max ZT0-3 6.953436666666667 5.02514 8.20763 ZT4-7 9.197624999999999 9.197624999999999 9.197624999999999 ZT8-11 14.9954 14.9954 14.9954 ZT12-15 15.026475000000001 14.51725 15.5357 ZT16-19 13.0063 13.0063 13.0063 ZT20-23 13.21695 13.21695 13.21695