condition mean min max ZT0-3 1.094816 1.094816 1.094816 ZT4-7 0.550962 0.550962 0.550962 ZT8-11 2.8196250000000003 2.8196250000000003 2.8196250000000003 ZT12-15 7.848955 7.848955 7.848955 ZT16-19 4.358805 4.358805 4.358805 ZT20-23 2.18077 2.18077 2.18077