condition mean min max ZT0-3 8.3 8.3 8.3 ZT4-7 10.8 10.8 10.8 ZT8-11 7.1 7.1 7.1 ZT12-15 9.05 9.05 9.05 ZT16-19 9.7 9.7 9.7 ZT20-23 15.4 15.4 15.4