condition mean min max ZT0-3 2.7 2.7 2.7 ZT4-7 3.2 3.2 3.2 ZT8-11 4.2 4.2 4.2 ZT12-15 3.25 3.25 3.25 ZT16-19 9.649999999999999 9.649999999999999 9.649999999999999 ZT20-23 7.85 7.85 7.85