There have been a few diaries this morning on turnout, so I thought I would provide a bit of data, based on turnout numbers and some percentages from a diary from earlier today.
From the U.S. Elections Project:
2006 40.4% total turnout, 85.7 million voters
2008 61.6% total turnout, 132.6 million
2010 40.9% total turnout, 90.7 million
This diary provides percentages of self identification by voters for 2006, 2008, and 2010. Combining the percentages in that table with the turnout numbers:
Data for liberals
2006 - 85.7 million voters x 20% liberal = 17.1 million liberals voted
2008 - 132.6 million voters x 22% liberal = 29.1 million liberals voted
2010 - 90.7 million voters x 20% liberal = 18.1 million liberals voted
Net change from 2006 to 2010: +1 million liberals
Net change from 2008 to 2010: -11 million liberals
Net change for turnout of liberal voters from 2008 to 2010: -37.8% of the 2008 total (-11 million / 29.1 million)
Data for moderates
2006 - 85.7 million voters x 47% moderate = 40.2 million moderates voted
2008 - 132.6 million x 44% moderate = 58.3 million moderates voted
2010 - 90.7 million x 38% moderate = 34.5 million moderates voted
Net change from 2006 to 2010: -5.7 million moderates
Net change from 2008 to 2010: -23.8 million moderates
Net change for turnout of moderate voters from 2008 to 2010: -40.8% of the 2008 total (-23.8 million / 58.3 million)
Data for conservatives
2006 - 85.7 million voters x 32% conservative = 27.4 million conservatives voted
2008 - 132.6 million x 34% conservative = 45.1 million conservatives voted
2010 - 90.7 million x 42% conservative = 38.1 million conservatives voted
Net change from 2006 to 2010: +10.7 million conservatives
Net change from 2008 to 2010: -7 million conservatives
Net change for turnout of conservative voters from 2008 to 2010: -15.5% of the 2008 total (-7 million / 45.1 million)
Overall numerical turnout for moderates was lower in 2010 than both 2006 or 2008. For liberals it was pretty constant between 2006 and 2010 but 2010 represented a significant decline compared with 2008. Conservatives were clearly demoralized in 2006 and didn't turn out heavily compared with either 2008 or 2010.
Looking over the past 2 main elections (2008 and 2010), there were fewer voters of all stripes in 2010 compared with 2008 - liberal, moderate, and conservative. However, the greatest dropoffs in numbers were seen among moderates first, then liberals, and conservatives had the least dropoff.
Liberals and moderates experienced a similar dropoff in 2010 voting as a percentage of 2008 voters. Both liberals and moderates experienced a decline in voters near 40% (the net change for turnout). This number was slightly higher for moderates than for liberals. The main difference in 2010 is that conservatives, while they also declined, did not decline as rapidly between 2008 and 2010 compared with the other two groups.
* Update *
I was asked elsewhere to add 2004 data, so here it is:
2004: overall 60.1% turnout, 123.5 million voters.
CNN Exit Poll for 2004 says:
Liberal 21%
Moderate 45%
Conservative 34%
So that makes the 2004 numbers...
Liberal = 21% x 123.5 million = 25.9 million
Moderate = 45% x 123.5 million = 55.6 million
Conservative = 34% x 123.5 million = 42 million
2004 to 2008 changes:
Liberal +3.2 million = +12.3%
Moderate +2.7 million = +4.9%
Conservative +3.1 million = +7.4%