condition mean min max ZT0-3 7.805417 7.805417 7.805417 ZT4-7 8.851167 8.851167 8.851167 ZT8-11 7.7624875 7.7624875 7.7624875 ZT12-15 8.057838 8.057838 8.057838 ZT16-19 8.0261885 8.0261885 8.0261885 ZT20-23 8.3628945 8.3628945 8.3628945