condition mean min max ZT0-3 1.9933016666666667 1.706235 2.143625 ZT4-7 3.5742200000000004 3.5742200000000004 3.5742200000000004 ZT8-11 4.659775 4.659775 4.659775 ZT12-15 2.55692 2.221335 2.892505 ZT16-19 2.2045700000000004 2.2045700000000004 2.2045700000000004 ZT20-23 3.33894 3.33894 3.33894