Reston, Va.—Online measurement company comScore has released a report highlighting the major trends in U.S. Internet activity last year among home, work and university Internet users.

The top property in terms of growth of visitors was Yellow Book Network, which increased 137% to 10.4 million visitors in December compared with December 2006.

Facebook.com, which opened its user base to all users last year, shot up 81% to 34.7 million visitors in December, compared with a year earlier.

Those properties were followed by Craigslist.org, Wikipedia and AT&T, which all posted healthy gains. AT&T’s 27% growth to 30.2 million visitors was aided by its deal with Apple to be the exclusive carrier for the iPhone.

Google continued its dominance and growth trajectory in search, with 5.6 billion searches in December, up 30% from the year-earlier period. Yahoo was a distant second with 2.2 billion searches, followed by Microsoft (940 million), Time Warner Network (442 million) and Ask Network (415 million).

More than 113 billion core searches were conducted in the U.S. in all of 2007, with Google sites accounting for nearly 64 billion, representing a 56% share of the market.

—Carol Krol