From UC Santa Cruz Professor G. William Domhoff: http://sociology.ucsc.edu/whorulesamerica/power/wealth.html
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 huge 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.