condition mean min max ZT0-3 8.253105 8.253105 8.253105 ZT4-7 10.002078999999998 10.002078999999998 10.002078999999998 ZT8-11 9.064025999999998 9.064025999999998 9.064025999999998 ZT12-15 9.260161 9.260161 9.260161 ZT16-19 9.321604 9.321604 9.321604 ZT20-23 8.431446999999999 8.431446999999999 8.431446999999999