condition mean min max ZT0-3 2.06616 2.06616 2.06616 ZT4-7 1.51087 1.51087 1.51087 ZT8-11 2.0472799999999998 2.0472799999999998 2.0472799999999998 ZT12-15 3.935445 3.935445 3.935445 ZT16-19 3.87107 3.87107 3.87107 ZT20-23 2.761023333333333 2.761023333333333 2.761023333333333