condition mean min max ZT0-3 18.102125 16.9446 19.25965 ZT4-7 9.280445 9.280445 9.280445 ZT8-11 7.775585 7.775585 7.775585 ZT12-15 0 0 0 ZT16-19 19.7487 19.7487 19.7487 ZT20-23 18.18775 18.18775 18.18775