On Jan-09-2013 the Tax Policy Center released its estimate of the number of estate tax return filings under current law (ATRA of 2012) for the years 2013 - 2022. A link to the Tax Policy Center web site is provided here, and links to the following 3 PDF files are available below:

T13-0019 - Estate Tax Returns and Liability Under Current Law and Various Reform Proposals, 2011-2022

T13-0020 - Current Law Distribution of Gross Estate and Net Estate Tax by Size of Gross Estate, 2013

T13-0021 - Current Law Distribution of Gross Estate and Net Estate Tax by Size of Gross Estate, 2022