Wendell Cox nicely summarizes the recent American Community Survey @ Newgeography: A Summary of 2011 Commuting Data Released Today :
"As estimated employment improved from 137.9 million in 2010 to 138.3 from 2010 to 2011, there was an increase of 800,000 in the number of commuters driving alone, which, as usual, represented the vast majority of commuting (105.6 million daily one way trips), at 76.40 percent. This was not enough, however, to avoid a small (0.17 percentage point) decline in market share.
Car pooling experienced a rare increase of 120,000 commuters, which translated into a 0.1 percentage point loss in market share, to 9.68 percent. Transit increased 190,000 commuters, and had a 0.09 percentage point increase in market share, to 5.03 percent. This brought transit's market share to above its 2008 share of 5.01 percent and near its 1990 market share of 5.11 percent.
Working at home increased by 70,000, with a modest 0.1 percentage point increase from 2010."