condition mean min max ZT0-3 12.1 12.1 12.1 ZT4-7 16.8 16.8 16.8 ZT8-11 12.6 12.6 12.6 ZT12-15 18.45 18.45 18.45 ZT16-19 21.8 21.8 21.8 ZT20-23 15.25 15.25 15.25