condition mean min max ZT0-3 6.1 6.1 6.1 ZT4-7 4.8 4.8 4.8 ZT8-11 3.85 3.85 3.85 ZT12-15 4.15 4.15 4.15 ZT16-19 11.6 11.6 11.6 ZT20-23 6.2 6.2 6.2