condition mean min max ZT0-3 4.030475 4.030475 4.030475 ZT4-7 2.96605 2.96605 2.96605 ZT8-11 2.2894300000000003 2.2894300000000003 2.2894300000000003 ZT12-15 3.525915 3.525915 3.525915 ZT16-19 4.82804 4.82804 4.82804 ZT20-23 4.5144649999999995 4.5144649999999995 4.5144649999999995