Here's a figure showing personal interest income received since the 1950s. The drop in interest payments received as personal income after the Federal Reserve cut interest rates to fight recession in 2001, and again in 2007-2008, are clearly visible.
To put this nominal data in a more revealing perspective, I've divided personal interest income by the size of the economy, as measured by GDP, which is a rough-and-ready way of adjusting for both economic growth and inflation over time. The result was striking:
The hump-shaped curve is striking to me. Back in the late 1940s, the main task of the Federal Reserve in the aftermath of World War II was to keep interest rates low so that government interest payments on the wartime debt would stay affordable. But the Fed broke lose from this arrangement and regained its independence with what is sometimes called the Treasury-Fed Accord of 1951. Interest rates rose, and so did the quantity of financial instruments paying interest, so the personal income received in the form of income rose, too.
During that period in the mid-1980s, personal income from interest payments was historically high relative to GDP. But since then, interest rates have gradually drifted lower, and during a number of time periods, the returns available from alternative investments in the stock market looked quite attractive. Personal income received in the form of interest payments has drifted lower, although not yet back to the level of the 1950s.