condition mean min max ZT0-3 21.893304 21.893304 21.893304 ZT4-7 22.294241 22.294241 22.294241 ZT8-11 19.0679405 19.0679405 19.0679405 ZT12-15 18.8688845 18.8688845 18.8688845 ZT16-19 18.2935645 18.2935645 18.2935645 ZT20-23 22.8024065 22.8024065 22.8024065