Well, I got curious and found an answer:
"In 1982, 60 percent of the people on the Forbes 400 list of wealthiest Americans came from wealthy families, compared with 32 percent in 2011."
http://www.gsb.stanford.edu/news/research/joshua-rauh-what-f...
"In 1982, 60 percent of the people on the Forbes 400 list of wealthiest Americans came from wealthy families, compared with 32 percent in 2011."
http://www.gsb.stanford.edu/news/research/joshua-rauh-what-f...
More to the point, it speaks nothing on how conditions for those not among the elite have changed in that time, and how they will change over time.