condition mean min max ZT0-3 17.559325 16.974800000000002 18.14385 ZT4-7 14.062 14.062 14.062 ZT8-11 16.12015 16.12015 16.12015 ZT12-15 0 0 0 ZT16-19 18.10065 18.10065 18.10065 ZT20-23 17.1167 17.1167 17.1167