The economy is getting stronger. Most Americans don't believe the economy is getting stronger. 

Both of those are true statements. But how? 

Here's a good way to show it.

This chart, from last week's Federal Reserve report on American household finances, shows the mean net worth of American households through 2012, adjusted for inflation: 

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Not bad. If this chart were more recent, it'd show a big boost since 2013 as the stock market roared higher. But the overall trend is clear: things have improved over the last two decades, by quite a bit. 

But that's the mean average -- the total amount of wealth divided by the number of households.

Now here's the median net worth of American families, representing families right in the middle of the pack: 

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Total disaster.

The overall economy has gotten far stronger, but the gains have gone to such a small number of households that the median American still thinks that things are getting worse. 

A lot of this has to do with the distribution of assets. Lower- and middle-income families tend to have a lot of their net worth tied up in their houses. As the housing bubble burst, that net worth was decimated and still hasn't rebounded. Upper-income families tend to have far more of their net worth in stocks. As the market hits new all-time highs, they're doing better than ever. In 2007, 1% of U.S. households owned more than 38% of the stocks owned by U.S. households. The bottom 90% of households owned just 18.8%.  

This trend probably won't go away, because the number of U.S. families able to put money in the stock market is massively tilted toward top earners. Consider the percentage of working-age families participating in a retirement plan: 

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Among families in the bottom half of income earners, fewer than 40% are saving for retirement. For those in the top 10% of earners, more than 90% are saving. 

All this means going forward is that there will be a disconnection between reports of "the economy" getting better, and most Americans shaking their heads as "their economy" continues to stagnate, or decline. 

Where do you stand on the spectrum? Here's a breakdown by income and net worth: 

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Contact Morgan Housel at mhosuel@fool.com. The Motley Fool has a disclosure policy.