Over the past few years, we've been hearing that consumer spending has begun to rise. During the recession, it plummeted as some Americans lost their jobs and others lost wealth as the stock market tanked and home values plummeted. When people feel poorer, they're less likely to spend as much money. This is as much common sense as economic theory. So you could further assert that once Americans feel as wealthy as they did before the recession, they'll begin spending aggressively again. Even though spending has begun to pick up a little, Americans still feel relatively poor.

The chart below tells this story. It was pinched from Federal Reserve Chairman Ben Bernanke's semiannual report to Congress.

The curve above shows the wealth-to-income ratio of Americans. That is, for every dollar they make, how much wealth they have. As of the first quarter of this year, the ratio stood at about five, meaning that for every dollar Americans earn, they have $5 in net worth.

You can see that the ratio suffered a pretty dramatic drop when the recession hit. It fell all the way from around 6.3 to about 4.6. Over the period shown, the ratio quickly went from its highest point to its lowest point.

Up to now, it hasn't made all that much progress. At five, it's only slightly above where it stood in the early 1990s, during which time the economy wasn't exactly flourishing. Both the dotcom and housing bubbles pushed this ratio up, in the late 1990s and early 2000s.

So what will it take for Americans to spend more? This chart provides your answer. They're continuing to save at a relatively elevated rate to rebuild their wealth. As you can see, if they want to get anywhere near where their wealth-to-income ratio stood over the past decade, then they have quite a lot of saving to go.