condition mean min max ZT0-3 19.265292 19.265292 19.265292 ZT4-7 18.476655 18.476655 18.476655 ZT8-11 22.2763225 22.2763225 22.2763225 ZT12-15 19.6997465 19.6997465 19.6997465 ZT16-19 21.992829 21.992829 21.992829 ZT20-23 19.373075999999998 19.373075999999998 19.373075999999998