Financial Soundness Indicator, Nonfinancial Corporations; Total Debt as a Percent of Equity, Level

An interesting item:

https://fred.stlouisfed.org/series/BOGZ1FL010000286Q

Since 1980 it looks like this:

Financial Soundness riding high, up near 100% since the financial crisis put FearOfGod into the nonfinancial corporate sector.

Yeah maybe, but this is how it looks since start-of-data:

I always want to know what happened before that!