condition mean min max ZT0-3 9.3 9.3 9.3 ZT4-7 14.8 14.8 14.8 ZT8-11 18.3 18.3 18.3 ZT12-15 30.4 30.4 30.4 ZT16-19 8.35 8.35 8.35 ZT20-23 6.0 6.0 6.0