condition mean min max ZT0-3 3.3175850000000002 3.3175850000000002 3.3175850000000002 ZT4-7 3.42044 3.42044 3.42044 ZT8-11 2.543735 2.543735 2.543735 ZT12-15 2.597715 2.597715 2.597715 ZT16-19 3.56696 3.56696 3.56696 ZT20-23 2.835 2.835 2.835