Those numbers don't mean anything as they don't tell you what parts of the proposed HTML 5 they refer to. Also HTML 5 might have changed since those numbers were produced and so browsers may or may not be supporting as much of HTML 5 as that chart suggests.
If the parts IE11 supports all end up in the standard and some of those are not supported by the others then IE11 might be the closest to supporting the final standard.
Anyway you can expect Microsoft to be cautious about supporting proposals before they become standard. They were the first to implement CSS 2 and a couple of significant things changed in between their implementation and CSS 2 becoming a standard resulting in quirks mode.
All that chart shows you is the likelihood of the browsers ending up with a new quirks mode through having implemented parts of HTML 5 that are still subject to change. Actually looking at how much has been implemented will only make sense once HTML 5 is actually finished.