condition mean min max ZT0-3 9.25 9.25 9.25 ZT4-7 2.3 2.3 2.3 ZT8-11 6.5 6.5 6.5 ZT12-15 3.3499999999999996 3.3499999999999996 3.3499999999999996 ZT16-19 7.4 7.4 7.4 ZT20-23 16.299999999999997 16.299999999999997 16.299999999999997