condition mean min max ZT0-3 8.060933 8.060933 8.060933 ZT4-7 8.055679 8.055679 8.055679 ZT8-11 8.993279000000001 8.993279000000001 8.993279000000001 ZT12-15 9.322927 9.322927 9.322927 ZT16-19 8.206952000000001 8.206952000000001 8.206952000000001 ZT20-23 8.571511000000001 8.571511000000001 8.571511000000001