condition mean min max ZT0-3 8.8 8.8 8.8 ZT4-7 3.7 3.7 3.7 ZT8-11 7.2 7.2 7.2 ZT12-15 3.1 3.1 3.1 ZT16-19 2.5 2.5 2.5 ZT20-23 17.9 17.9 17.9