condition mean min max ZT0-3 3.36516 3.36516 3.36516 ZT4-7 2.986415 2.986415 2.986415 ZT8-11 4.1869250000000005 4.1869250000000005 4.1869250000000005 ZT12-15 2.50945 2.50945 2.50945 ZT16-19 2.283845 2.283845 2.283845 ZT20-23 2.54642 2.54642 2.54642