condition mean min max ZT0-3 18.112676 18.112676 18.112676 ZT4-7 13.299710999999999 13.299710999999999 13.299710999999999 ZT8-11 15.3809065 15.3809065 15.3809065 ZT12-15 16.5621965 16.5621965 16.5621965 ZT16-19 13.9103695 13.9103695 13.9103695 ZT20-23 16.3498295 16.3498295 16.3498295