condition mean min max ZT0-3 6.620939482 3.2117158569999997 10.030163107 ZT4-7 14.886141995 11.487830205 18.284453785 ZT8-11 11.59719067375 9.093305623000001 14.1010757245 ZT12-15 1.62328113675 0.777972958 2.4685893155 ZT16-19 0.73235776675 0.7185843005 0.746131233 ZT20-23 0.94892242175 0.941432142 0.9564127014999999