condition mean min max ZT0-3 7.662721666666666 7.094609999999999 8.465364999999998 ZT4-7 3.941345 3.941345 3.941345 ZT8-11 4.59016 4.59016 4.59016 ZT12-15 6.765772500000001 5.766935 7.76461 ZT16-19 8.101135 8.101135 8.101135 ZT20-23 8.652915 8.652915 8.652915