condition mean min max ZT0-3 2.09938461225 1.8649689705 2.3338002540000002 ZT4-7 5.356725571749999 4.879999685 5.833451458499999 ZT8-11 5.683353051 5.6080532825 5.7586528195 ZT12-15 9.162295903 7.622700794 10.701891012 ZT16-19 18.186021142500003 16.060905855 20.31113643 ZT20-23 23.23020627 22.122366235 24.338046305