condition mean min max ZT0-3 2.569328333333333 2.2118349999999998 2.9693899999999998 ZT4-7 1.959905 1.959905 1.959905 ZT8-11 2.94643 2.94643 2.94643 ZT12-15 4.881485 4.8012 4.96177 ZT16-19 4.196685 4.196685 4.196685 ZT20-23 4.518345 4.518345 4.518345