condition mean min max ZT0-3 4.255515 3.740995 4.770035 ZT4-7 3.817235 3.817235 3.817235 ZT8-11 6.40882 6.40882 6.40882 ZT12-15 0 0 0 ZT16-19 7.638035 7.638035 7.638035 ZT20-23 5.799715 5.799715 5.799715