condition mean min max ZT0-3 1.998775 1.998775 1.998775 ZT4-7 1.72642 1.72642 1.72642 ZT8-11 2.388985 2.388985 2.388985 ZT12-15 2.2200349999999998 2.2200349999999998 2.2200349999999998 ZT16-19 2.58466 2.58466 2.58466 ZT20-23 2.3918850000000003 2.3918850000000003 2.3918850000000003