Have there been studies on this?

What has happened to the allocation of disposable income through the generations?
I'm taking a generation to be a period of 20 years
and I would exclude the first 20 years because until a person is at least 20, they generally attach very little importance to what they do with their spare money ie. whatever is left after paying board or rent + food, fares, clothes etc.

I'm not going to give you the answers, I don't know if the statistics even exist, but probably there have been studies. Academics have to generate studies to advance, plus research companies exist to feed businesses with statistics on trends in disposable income.

It would be interesting to know what the trend is. Did people in earlier generations save more of their income than people today? Or has it been a fairly level trend throughout?
We all know, or think so, that the economy is pretty tight today, especially if you have to rent or even share.

Views anybody?