In 1975 about 7 million workers claimed disability benefits via the two main disability programs run by the federal government: Supplemental Security Income (SSI) and Disability Insurance (DI). In the most recent year more than 16 million workers claimed disability benefits, amounting to about 5% of the population:
Disability benefits have grown slowly since the early '90s. DI benefits currently average about $1,500 per month while SSI benefits average about $500 per month. Taken together, the two programs pay out an average of $1,000 per month:
Disability programs were a frequent target of "crisis frenzy" up until 2015. Partly this was because applications had doubled between 2000 and 2010; partly because of concerns that applications for childrens' disability were being abused; and partly because the Disability Insurance trust fund was in dire shape. However, in 2013 applications suddenly began to decline for reasons that remain unclear, and that in turn saved the DI trust fund. Today the program's financial footing is secure for at least another decade.
Data comes from the Social Security Administration here and here and from Wikipedia here.
UPDATE: The initial version of this post accounted only for DI outlays. I've updated it to include both DI and SSI.
I think you're mixing up SSDI and SSI. Second chart is definitely SSDI, and the trust fund is a DI issue not a SSI issue. Is the first one also SSI?
You are correct. Second chart has to be SSDI since the monthly maximum SSI amount for 2021 is $794 for an eligible individual. So no way the annual benefits would be that high. It is currently so difficult to get SSDI or SSI, but I don't know if has always been that way.