condition mean min max ZT0-3 8.1234025 7.65062 8.596184999999998 ZT4-7 7.635149999999999 7.635149999999999 7.635149999999999 ZT8-11 7.89011 7.89011 7.89011 ZT12-15 0 0 0 ZT16-19 9.214020000000001 9.214020000000001 9.214020000000001 ZT20-23 8.982330000000001 8.982330000000001 8.982330000000001