condition mean min max ZT0-3 2.853485 1.19955 3.851855 ZT4-7 0.6667775 0.6667775 0.6667775 ZT8-11 2.381965 2.381965 2.381965 ZT12-15 0.96730425 0.8311645 1.103444 ZT16-19 2.534615 2.534615 2.534615 ZT20-23 3.86463 3.86463 3.86463