condition mean min max ZT0-3 6.993855 6.993855 6.993855 ZT4-7 3.34898 3.34898 3.34898 ZT8-11 5.46429 5.46429 5.46429 ZT12-15 6.6637 6.6637 6.6637 ZT16-19 9.279264999999999 9.279264999999999 9.279264999999999 ZT20-23 8.273055 8.273055 8.273055