What percent of elderly live with their children?

In the past; widows, widowers moved in with their children - at least from what I've heard ad hoc. I'm looking for the percentage of elderly who moved with a children in modern times. Would love to see the trends from early 1900's to today. I tried to find this at Census site - but became overwhelmed by other data. I've also heard that the affluent tend to send their parents to nursing homes rather than take them in. Any idea where I can find statistics on this?