condition mean min max ZT0-3 6.2370149999999995 6.2370149999999995 6.2370149999999995 ZT4-7 4.89482 4.89482 4.89482 ZT8-11 5.08748 5.08748 5.08748 ZT12-15 6.32365 6.32365 6.32365 ZT16-19 7.06833 7.06833 7.06833 ZT20-23 6.414245 6.414245 6.414245