condition mean min max ZT0-3 2.25 2.25 2.25 ZT4-7 4.5 4.5 4.5 ZT8-11 13.5 13.5 13.5 ZT12-15 29.6 29.6 29.6 ZT16-19 23.65 23.65 23.65 ZT20-23 18.15 18.15 18.15