condition mean min max ZT0-3 7.537585 7.537585 7.537585 ZT4-7 5.868565 5.868565 5.868565 ZT8-11 10.030125 10.030125 10.030125 ZT12-15 10.05574 10.05574 10.05574 ZT16-19 11.997 11.997 11.997 ZT20-23 9.25727 9.25727 9.25727