condition mean min max ZT0-3 2.447165 2.447165 2.447165 ZT4-7 1.64967 1.64967 1.64967 ZT8-11 2.44845 2.44845 2.44845 ZT12-15 2.6824000000000003 2.6824000000000003 2.6824000000000003 ZT16-19 4.3269850000000005 4.3269850000000005 4.3269850000000005 ZT20-23 2.30289 2.30289 2.30289