condition mean min max ZT0-3 3.0 3.0 3.0 ZT4-7 2.1 2.1 2.1 ZT8-11 2.75 2.75 2.75 ZT12-15 9.7 9.7 9.7 ZT16-19 3.3499999999999996 3.3499999999999996 3.3499999999999996 ZT20-23 30.049999999999997 30.049999999999997 30.049999999999997