condition mean min max ZT0-3 17.321896 17.321896 17.321896 ZT4-7 15.6952885 15.6952885 15.6952885 ZT8-11 15.603299 15.603299 15.603299 ZT12-15 13.539281500000001 13.539281500000001 13.539281500000001 ZT16-19 15.8227595 15.8227595 15.8227595 ZT20-23 17.31942 17.31942 17.31942