condition mean min max ZT0-3 20.75 20.75 20.75 ZT4-7 3.5 3.5 3.5 ZT8-11 5.4 5.4 5.4 ZT12-15 2.2 2.2 2.2 ZT16-19 3.9000000000000004 3.9000000000000004 3.9000000000000004 ZT20-23 2.2 2.2 2.2