condition mean min max ZT0-3 15.6 15.6 15.6 ZT4-7 2.6 2.6 2.6 ZT8-11 1.7 1.7 1.7 ZT12-15 18.75 18.75 18.75 ZT16-19 9.1 9.1 9.1 ZT20-23 2.75 2.75 2.75