condition mean min max ZT0-3 5.637255 5.637255 5.637255 ZT4-7 4.835735 4.835735 4.835735 ZT8-11 6.25966 6.25966 6.25966 ZT12-15 5.1536100000000005 5.1536100000000005 5.1536100000000005 ZT16-19 7.01119 7.01119 7.01119 ZT20-23 5.2616499999999995 5.2616499999999995 5.2616499999999995