condition mean min max ZT0-3 1.7710066666666666 1.436135 2.209535 ZT4-7 1.065505 1.065505 1.065505 ZT8-11 1.940795 1.940795 1.940795 ZT12-15 5.1075 4.73754 5.47746 ZT16-19 4.4948049999999995 4.4948049999999995 4.4948049999999995 ZT20-23 3.7242499999999996 3.7242499999999996 3.7242499999999996