condition mean min max ZT0-3 8.953163 8.953163 8.953163 ZT4-7 9.341032 9.341032 9.341032 ZT8-11 9.21817 9.21817 9.21817 ZT12-15 9.311905 9.311905 9.311905 ZT16-19 9.437844 9.437844 9.437844 ZT20-23 10.473913 10.473913 10.473913