thank you 

 I would argue based on the data you presented (thank you) that the deaths in the 80's and 90's up to 2000 where mostly 30/40/50 y.o. gay men (assume all where gay men of course that was not the case) thus they had paid in a long time. Taking .5 million people (very sad) at a ss tax max of 5k per year for only 10 years is 250 million. So that is money that "freed up" since their were no spouse to collect it. 

  As a side note correct me if I am wrong the social security trust fund became assesable for government use (regan) right around the time AIDS appeared?