condition mean min max ZT0-3 7.672066 7.672066 7.672066 ZT4-7 8.244665 8.244665 8.244665 ZT8-11 8.35194 8.35194 8.35194 ZT12-15 7.4993625 7.4993625 7.4993625 ZT16-19 7.740642 7.740642 7.740642 ZT20-23 7.503921500000001 7.503921500000001 7.503921500000001