condition mean min max ZT0-3 7.0 7.0 7.0 ZT4-7 6.1 6.1 6.1 ZT8-11 3.45 3.45 3.45 ZT12-15 6.3 6.3 6.3 ZT16-19 8.3 8.3 8.3 ZT20-23 3.3 3.3 3.3