condition mean min max ZT0-3 6.300000000000001 6.300000000000001 6.300000000000001 ZT4-7 7.7 7.7 7.7 ZT8-11 5.35 5.35 5.35 ZT12-15 24.3 24.3 24.3 ZT16-19 21.049999999999997 21.049999999999997 21.049999999999997 ZT20-23 4.5 4.5 4.5