condition mean min max ZT0-3 18.6645 18.6645 18.6645 ZT4-7 15.667000000000002 15.667000000000002 15.667000000000002 ZT8-11 15.286249999999999 15.286249999999999 15.286249999999999 ZT12-15 15.1675 15.1675 15.1675 ZT16-19 20.4773 20.4773 20.4773 ZT20-23 25.632 25.632 25.632