condition mean min max ZT0-3 2.8417000000000003 2.8417000000000003 2.8417000000000003 ZT4-7 1.663975 1.663975 1.663975 ZT8-11 1.7229999999999999 1.7229999999999999 1.7229999999999999 ZT12-15 2.430815 2.430815 2.430815 ZT16-19 2.9146799999999997 2.9146799999999997 2.9146799999999997 ZT20-23 2.406935 2.406935 2.406935