condition mean min max ZT0-3 4.117865 4.117865 4.117865 ZT4-7 3.561975 3.561975 3.561975 ZT8-11 2.39845 2.39845 2.39845 ZT12-15 3.9166849999999998 3.9166849999999998 3.9166849999999998 ZT16-19 3.341555 3.341555 3.341555 ZT20-23 4.392165 4.392165 4.392165