condition mean min max ZT0-3 6.85 6.85 6.85 ZT4-7 1.6 1.6 1.6 ZT8-11 7.65 7.65 7.65 ZT12-15 11.2 11.2 11.2 ZT16-19 6.5 6.5 6.5 ZT20-23 6.55 6.55 6.55