condition mean min max ZT0-3 2.1 2.1 2.1 ZT4-7 6.1 6.1 6.1 ZT8-11 4.1 4.1 4.1 ZT12-15 3.75 3.75 3.75 ZT16-19 2.3 2.3 2.3 ZT20-23 3.8 3.8 3.8