If you take this chart at face value, the establishment press meme of a "center-right" nation begins to look accurate.
The polling indicates that there are twice as many self-identified conservatives and moderates than liberals. In fact, the liberal numbers look downright dismal. But it's important to remember that this is mostly about branding and not actual ideology. If you ask Americans about individual issues and policies, most people are center-left -- much more liberal than this narrow chart indicates.
Sorry, wingnuts, but single-issue polls indicate that Americans tend to support a woman's right to choose, they tend to support government programs like Medicare and Medicaid, they tend to support gun control laws, they tend to support government regulation of industry, they tend to support labor laws, they tend to be against endless war, they tend to support healthcare reform and the public option, etc, etc.
It's just that the word "liberal" continues to be synonymous with "wimpy" or "weak."