condition mean min max ZT0-3 7.468502861999999 7.137396530999999 7.799609193 ZT4-7 6.417476623 6.209337243 6.625616002999999 ZT8-11 7.992974423833333 7.380875654333333 8.605073193333332 ZT12-15 7.852078707833334 7.264130887666667 8.440026528 ZT16-19 10.7577165735 10.348922224333332 11.166510922666667 ZT20-23 9.698965611 8.26475992 11.133171302000001