condition mean min max ZT0-3 5.3 5.3 5.3 ZT4-7 2.8 2.8 2.8 ZT8-11 6.7 6.7 6.7 ZT12-15 9.85 9.85 9.85 ZT16-19 14.9 14.9 14.9 ZT20-23 6.6 6.6 6.6