condition mean min max ZT0-3 8.1 8.1 8.1 ZT4-7 3.2 3.2 3.2 ZT8-11 6.9 6.9 6.9 ZT12-15 3.95 3.95 3.95 ZT16-19 8.7 8.7 8.7 ZT20-23 6.6 6.6 6.6