condition mean min max ZT0-3 17.156443 17.156443 17.156443 ZT4-7 15.009949 15.009949 15.009949 ZT8-11 14.0904785 14.0904785 14.0904785 ZT12-15 15.254562499999999 15.254562499999999 15.254562499999999 ZT16-19 13.044874499999999 13.044874499999999 13.044874499999999 ZT20-23 18.496717 18.496717 18.496717