Where can i find a historical chart of equity vs mortgage percentage of home values?

Let’s say that a home is worth 1 million dollars according to current estimates. If the owner has $800k in mortgages his home equity is 20%.

Are there any charts or graphs that show what the average home equity is on a historical timeline, specifically for the USA?

I’d like to know if Americans are fully maxed out on their home equity with full refinancing, or if they have a lot of equity built up in their homes.

Knowing what the average equity percentage is of USA homes over a timeline would help predict foreclosure rates in the event of a substantial home price reduction in the future.