condition mean min max ZT0-3 6.341248333333333 3.78823 8.786674999999999 ZT4-7 3.1777300000000004 3.1777300000000004 3.1777300000000004 ZT8-11 2.70583 2.70583 2.70583 ZT12-15 5.070945 4.637505 5.504385 ZT16-19 5.1878400000000005 5.1878400000000005 5.1878400000000005 ZT20-23 6.429035000000001 6.429035000000001 6.429035000000001