condition mean min max ZT0-3 1.6670295 0.6449885 2.660475 ZT4-7 0.1995535 0.1995535 0.1995535 ZT8-11 0.55179 0.55179 0.55179 ZT12-15 1.9725175000000001 1.4666700000000001 2.478365 ZT16-19 2.8741899999999996 2.8741899999999996 2.8741899999999996 ZT20-23 3.54428 3.54428 3.54428