condition mean min max ZT0-3 20.22705 18.928 21.5261 ZT4-7 20.418100000000003 20.418100000000003 20.418100000000003 ZT8-11 22.27145 22.27145 22.27145 ZT12-15 0 0 0 ZT16-19 19.674500000000002 19.674500000000002 19.674500000000002 ZT20-23 19.79665 19.79665 19.79665