condition mean min max ZT0-3 11.25 11.25 11.25 ZT4-7 18.5 18.5 18.5 ZT8-11 8.9 8.9 8.9 ZT12-15 18.15 18.15 18.15 ZT16-19 14.3 14.3 14.3 ZT20-23 18.05 18.05 18.05