condition mean min max ZT0-3 7.548741 7.548741 7.548741 ZT4-7 9.190974 9.190974 9.190974 ZT8-11 8.8105095 8.8105095 8.8105095 ZT12-15 8.5802195 8.5802195 8.5802195 ZT16-19 8.306027 8.306027 8.306027 ZT20-23 8.207587499999999 8.207587499999999 8.207587499999999