NAR reports Canadians represent 23% of foreign home buyers, here is an excert from the article:

Recent international buyers came from 70 different countries, up from 53 countries in 2010. For the fourth consecutive year, Canada was the top country of origin, with 23 percent of sales to foreigners.

The average price paid by an international buyer was $315,000 compared to the overall U.S. average of $218,000. Florida had 31 percent of total international transactions this year, the most of any state. California had 12 percent, Texas had nine percent, and Arizona rounded out the top four with six percent of international transactions.

Foreign buyers are primarily interested in three factors when deciding where to buy in the U.S.: proximity to their home country; convenience of air transportation; and climate and location.

View the full article: http://www.realtor.org/press_room/news_releases/2011/05/foreign_buyers