condition mean min max ZT0-3 8.609035 8.609035 8.609035 ZT4-7 6.019905 6.019905 6.019905 ZT8-11 6.258775 6.258775 6.258775 ZT12-15 8.82555 8.82555 8.82555 ZT16-19 12.3249 12.3249 12.3249 ZT20-23 8.95185 8.95185 8.95185