condition mean min max ZT0-3 1.9 1.9 1.9 ZT4-7 3.8 3.8 3.8 ZT8-11 7.699999999999999 7.699999999999999 7.699999999999999 ZT12-15 2.55 2.55 2.55 ZT16-19 3.3 3.3 3.3 ZT20-23 3.55 3.55 3.55