condition mean min max ZT0-3 4.402795 3.544705 5.260885 ZT4-7 5.553125 5.553125 5.553125 ZT8-11 24.26775 24.26775 24.26775 ZT12-15 0 0 0 ZT16-19 22.421750000000003 22.421750000000003 22.421750000000003 ZT20-23 11.06985 11.06985 11.06985