condition mean min max ZT0-3 7.6 7.6 7.6 ZT4-7 3.0 3.0 3.0 ZT8-11 5.5 5.5 5.5 ZT12-15 9.0 9.0 9.0 ZT16-19 5.3 5.3 5.3 ZT20-23 8.2 8.2 8.2