condition mean min max ZT0-3 9.605427 9.605427 9.605427 ZT4-7 8.3267725 8.3267725 8.3267725 ZT8-11 8.945562500000001 8.945562500000001 8.945562500000001 ZT12-15 8.750081000000002 8.750081000000002 8.750081000000002 ZT16-19 8.0919645 8.0919645 8.0919645 ZT20-23 9.682067499999999 9.682067499999999 9.682067499999999