condition mean min max ZT0-3 2.55 2.55 2.55 ZT4-7 2.3 2.3 2.3 ZT8-11 17.4 17.4 17.4 ZT12-15 2.05 2.05 2.05 ZT16-19 3.1500000000000004 3.1500000000000004 3.1500000000000004 ZT20-23 1.75 1.75 1.75