The graph is basically meaningless, because all it shows are the taxes paid, and not the taxes needed.
The nation is falling apart because we are not collecting the taxes we need to fix things, to build new things, and to properly take care of our people. Not taxing the wealthy is not so much a problem of the ratio of taxes being paid (as the right wing shills for the rich always want to insist), it's a problem of starving the government of the money it needs to run a very big, very complex, and very powerful nation, as it needs to and should be run, just so that the very rich can become even richer.
And this isn't an issue of "fairness" as much as it's an issue of simple necessity. If we keep starving the government so the very rich can become even richer, they will simply buy the government (they already have, basically) and we will be living in an oligarchy (we pretty much already are). And oligarchies inevitably strangle their people, economically. Which is exactly what's going on.