condition mean min max ZT0-3 3.7 3.7 3.7 ZT4-7 2.8 2.8 2.8 ZT8-11 10.8 10.8 10.8 ZT12-15 4.15 4.15 4.15 ZT16-19 2.3499999999999996 2.3499999999999996 2.3499999999999996 ZT20-23 1.75 1.75 1.75