Of the approximately $1.07 trillion in existing-home sales between March 2010 and March 2011, approximate $41 billion dollars-worth were purchased by foreign buyers.
Recent immigrants—those who have moved to the U.S. within the past 2 years—and individuals with visas for more than 6 months, purchased an additional $41 billion.
Therefore, total purchases by foreign or foreign-born buyers were $82 billion, up from $66 billion reported in 2010.

NAR - 2011 International Home Buying Activity