Historical US Estate Taxes

With the exception of death and taxes, nothing in life is certain.  If in life you accumulate some substantial assets (real estate, a business, savings and investments) and you live in a country that levies an estate tax, the former may trigger more of the latter!

Estate taxes are levied on the total current value of all of the junk you leave behind.  Anything you leave to a nonprofit organization or to your spouse is exempt, and there are additional rules to protect family businesses, farms, and the like.

Digging back through seventy years of Congressional tax reform records (1), I was able to reconstruct the historical estate tax rates, brackets, and exemptions back through 1942 (2).  I used a dizzying array of spreadsheet functions to correct for inflation and generate this graphic of historical effective tax rates:
US historical estate tax rates. y-axis is year (2013 on top); x-axis is estate size ($0-127,000,000); each color is 8%
The scale on this graphic is truly massive, including the effective tax rates of estate sizes up to $127 million on the far right.  I considered using a log scale, but I wanted to stick to a linear scale to make this graph comparable with my Historical US Income Tax infographic.

The top estate tax rate from 1947-1976 was 77%; the top rate dropped to 55% for most of the 1980's and 1990's and now sits at 40%.  Meanwhile, the inflation-adjusted estate tax exemption limit - the estate size on which no taxes are paid - has risen substantially:
Estate tax effective rate declines began with Reagan's Economic Recovery Act (ERTA) of 1981 (3) and continued with George W. Bush's Economic Growth and Tax Relief Reconciliation Act (EGTRRA) of 2001 (4).  EGTRRA contained provisions that phased out the estate tax between 2001-2009, ending in the complete repeal of estate tax in 2010.  The estate tax was repealed in 2010, only to be reinstated in Obama's Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act (TRUIRJCA) of 2010 (5).

(1) http://en.wikipedia.org/wiki/Category:United_States_federal_taxation_legislation
(2) https://docs.google.com/spreadsheet/ccc?key=0AiEk9zzYZVLgdDRBcEE1dndoVGVQWDZBVjduNmV2UlE#gid=4
(3) http://en.wikipedia.org/wiki/Economic_Recovery_Tax_Act_of_1981
(4) http://en.wikipedia.org/wiki/Economic_Growth_and_Tax_Relief_Reconciliation_Act_of_2001
(5) http://en.wikipedia.org/wiki/Tax_Relief,_Unemployment_Insurance_Reauthorization,_and_Job_Creation_Act_of_2010