condition mean min max ZT0-3 7.297745 7.297745 7.297745 ZT4-7 5.635915 5.635915 5.635915 ZT8-11 1.837045 1.837045 1.837045 ZT12-15 2.81909 2.81909 2.81909 ZT16-19 12.31636 12.31636 12.31636 ZT20-23 9.164625000000001 9.164625000000001 9.164625000000001