Excess Reserves: Increasing Since 1980

This, you know:

Graph #1: Excess Reserves

The FRED page Excess Reserves of Depository Institutions says

Excess reserves equals total reserves less required reserves.

So instead of looking at the excess, I switched it around to see the NOT-excess part as a percent of total reserves:

Graph #2: The part of Reserves that's NOT excess

Above the blue line, up to 100%, is Excess Reserves. Below the blue line is Required Reserves. Almost binary, isn't it? Switching, like a transistor. Before the financial crisis it was on. Now it's off.

I want to look at the "on" part.

I cropped the graph at 2008 to remove the explosive increase in reserves. But the downspike of the 2001 recession still pushed earlier-year reserves way up to the top of the graph. So I cropped it back to 2000. FRED left a blank spot at the end of the plot area. FRED likes to work in decades or something. 1959-1999 filled the plot area nicely:

Graph #3: Required Reserves as a Percent of Total Reserves, 1 January 1959 thru 31 January 1999

General increase from 1959 to 1970. Then it runs flat at ninety-nine and one-half out of a hundred until 1980. Then it starts to come down.

There is a significant down-spike during the 1990 recession. It is visible, barely, on Graph #2. Well look at that! There are significant downspikes in the last THREE recessions shown on Graph #2. And, come to think of it, there are a couple tremors there, between the 2001 and 2008 downspikes.