condition mean min max ZT0-3 8.847994 8.847994 8.847994 ZT4-7 8.3026985 8.3026985 8.3026985 ZT8-11 8.041234 8.041234 8.041234 ZT12-15 8.3793275 8.3793275 8.3793275 ZT16-19 7.9476525 7.9476525 7.9476525 ZT20-23 10.6024175 10.6024175 10.6024175