condition mean min max ZT0-3 16.621521 16.621521 16.621521 ZT4-7 21.74129 21.74129 21.74129 ZT8-11 18.222656999999998 18.222656999999998 18.222656999999998 ZT12-15 25.5996925 25.5996925 25.5996925 ZT16-19 12.741256499999999 12.741256499999999 12.741256499999999 ZT20-23 10.2102825 10.2102825 10.2102825