condition mean min max ZT0-3 13.7 13.7 13.7 ZT4-7 2.9 2.9 2.9 ZT8-11 15.55 15.55 15.55 ZT12-15 4.0 4.0 4.0 ZT16-19 5.8 5.8 5.8 ZT20-23 23.6 23.6 23.6