Wealth Concentration: As of 2007, the top 1% of households (the upper class) owned 34.6% of all privately held wealth, and the next 19% (the managerial, professional, and small business stratum) had 50.5%, which means that just 20% of the people owned a remarkable 85%, leaving only 15% of the wealth for the bottom 80% (wage and salary workers)
Estate Tax: Figures on inheritance tell much the same story. According to a study published by the Federal Reserve Bank of Cleveland, only 1.6% of Americans receive $100,000 or more in inheritance. Another 1.1% receive $50,000 to $100,000. On the other hand, 91.9% receive nothing (Kotlikoff & Gokhale, 2000). Thus, the attempt by ultra-conservatives to eliminate inheritance taxes -- which they always call "death taxes" for P.R. reasons -- would take a bite out of government revenues for the benefit of less than 1% of the population.
You should read the entire article (click on link above). The charts are especially fascinating.
Update: per the Federal Reserve Bulletin (September 2014, Vol 100, No 4) aka the 2013 Tri-Annual Survey of Consumer Finances from 2010 to 2013, about 1 in 5 American families earns over 100,000 USD each year.
As of 2013, if you are between 18 to 35 years old and your net worth is more than 10,400 USD, you are better off than half of all American families in your age group.