You should define "vacation time". I don't know much about the history of leisure time, but I imagine that people have different ideas as to what it is over the eras. Also, you might want to think about if "vacation time" is even relevant to GWB and Obama since they could do there job anywhere on Earth thanks to technology.

Finally, you should think about whether or not you want to release something where the sources are what the internet will give you. Honestly, I think you are close to being academically irresponsible.

By "does it look okay?" I mean "does it look accurate?"

Just curious: where did you get these figures, and why did you choose these presidents? Would it be possible to include more presidents in a more readable format?