condition mean min max ZT0-3 6.1 6.1 6.1 ZT4-7 1.5 1.5 1.5 ZT8-11 7.6000000000000005 7.6000000000000005 7.6000000000000005 ZT12-15 8.1 8.1 8.1 ZT16-19 3.05 3.05 3.05 ZT20-23 5.55 5.55 5.55