Retailers and other advertisers got more clicks from Google ads in the fourth quarter and paid less per click, Google Inc. reported today in disclosing its fourth quarter and full-year 2011 financial results.

Paid clicks during the fourth quarter ending Dec. 31 jumped 34% compared with last year and 17% compared with the third quarter, the search engine giant reported today. Average cost per click decreased approximately 8% compared with the fourth quarter of 2010 and by the same amount compared with the third quarter of 2011.

Google reported revenue of $10.58 billion in the fourth quarter, a 25.4% increase compared with $8.44 billion in the same period last year. Net income in the fourth quarter reached $2.71 billion, up 6.7% compared to $2.54 billion last year. For the full year 2011, Google reported $37.9 billion in revenue, up 29.3% from $29.3 billion in 2010. Net income was $9.7 billion, a 14.1% increase compared with $8.5 billion in 2010.

Google also reported gains in two of its major initiatives in the social and mobile arenas. Google Inc.’s social network Google+, which it launched in June, now has 90 million global users, more than double the number of three months ago, CEO Larry Page told analysts today.

Additionally, 250 million total Android mobile devices have been activated, Page said, with 50 million activated in the last two months.

“I am super excited about the growth of Android, Gmail, and Google,” he said. “By building a meaningful relationship with our users through Google+ we will create amazing experiences across our services.”

Google-owned sites, such as the Google.com search engine and YouTube, contributed 68.9% or $7.3 billion of total revenue, a 28.6% increase compared with the fourth quarter of 2010. Revenue from outside of the United States amounted to $5.6 billion in the fourth quarter. That represents 52.9% of total revenue for the quarter, compared with 54.5% in the third quarter of 2011, and with 52.0% for fourth quarter of 2010.