condition mean min max ZT0-3 9.296049 9.296049 9.296049 ZT4-7 8.2956555 8.2956555 8.2956555 ZT8-11 8.260846 8.260846 8.260846 ZT12-15 7.691660000000001 7.691660000000001 7.691660000000001 ZT16-19 7.5559125 7.5559125 7.5559125 ZT20-23 8.8031135 8.8031135 8.8031135