condition mean min max ZT0-3 2.3 2.3 2.3 ZT4-7 2.0 2.0 2.0 ZT8-11 14.75 14.75 14.75 ZT12-15 15.8 15.8 15.8 ZT16-19 6.45 6.45 6.45 ZT20-23 20.55 20.55 20.55