Income Disparity - Then and Now

I've written several posts on income disparity using data provided by the CBO. In short, the US is a society of the haves and have-nots, and the haves have accumulated more and more of the income for themselves over the years.

I've heard it mentioned several times before that income disparity was especially bad right before the Great depression. Unfortunately the CBO data only goes back to 1979, and thus all of the analysis I've done on the CBO data is quite limited in scope.

Anyway, I happened upon a post the other day at Jesse's Café Américain on the Minsky moment. The post itself is definitely worth reading, since we may be living through a Minsky moment as I write this. At the bottom of the post, though, was a figure breaking down income by quintile in some of the years prior to the Great Depression. It's not year by year, but it will do:
I decided to reorganize the data so that it matched the format in which I've presented the CBO data before. Here it is:

Unfortunately, there are only three years, but you can see that there is a general trend that income distributed to the highest quintile has steadily increased at the expense of the bottom 80% of the population. This is strikingly similar to what has happened since 1979.

This is pretax income, which what was used in the figure for the preGreat Depression data. As you can see, it's the same trend leading up to the Great Depression: an increase in share of income for the top 20% and a decrease for everyone else.

What's especially striking is when you break down the top 20% into various categories: Top 1%, Top 5%-1%, Top 10%-5%, and Top 20%-10%.

The amazing thing is that the share of income has only increased for the wealthiest of the wealthy. In fact, the Top 1%, representing only 1% of the population, was earning less than 10% of total income in 1979. In 2005, the Top 1% was earning more than 18%.

It's clear that we live in a society made up of the ultra-wealthy and everyone else, and that the ultra-wealthy has only become even wealthier in recent years. It particularly interesting that incomes during the period of time leading up to the Great Depression reflected a similar pattern of income. I'm not suggesting that the current credit crunch will lead to a Second Great Depression. But I hope that one of the results of the current crisis is realignment of this disparity so that the wealth of the nation benefits the commonwealth and not just the moneyed few.

I'd love to find a full data set that includes income broken down by quintile that goes back all the way before the great depression. If anyone knows where to find these data, please let me know in comments.