Each month, Nielsen tracks U.S. internet usage as well as the top U.S. web brands. Taking a look at the results of the Nielsen analysis and comparing January 2011 data to December 2011 data, there are a couple of things that stand out. First, internet usage continues to grow. Second, the top online brands are sitting pretty in their leadership places with little threat to their web dominance.Let's take a closer look.First, in January 2011 and December 2011, the top 6 U.S. web brands stayed the same. Of the bottom four U.S. web brands that made up the top 10 list in January 2011 and December 2011, only one brand dropped off the list and was replaced. The others simply shuffled positions. Both top 10 lists are shown below with the number of unique U.S. people who visited each site and the average time per person (hh:mm:ss) spent on each site.

January 2011

1. Google = 153.6 million (1:21:00)
2. Facebook = 135.6 million (7:24:12)
3. Yahoo! = 130.9 (2:20:10)
4. MSN/Windows Live/Bing = 121.0 million (1:26:39)
5. YouTube = 103.9 million (1:21:54)
6. Microsoft = 90.2 million (0:41:53)
7. AOL Media Network = 76.2 million (1:58:31)
8. Wikipedia = 65.7 million (1:15:31)
9. Ask Search Network = 65.5 million (0:10:40
10. Apple = 63.3 million (1:18:48)

December 2011

1. Google = 173.3 million (1:36:42)
2. Facebook = 153.4 (6:51:09)
3. Yahoo! 144.2 million (2:17:14)
4. MSN/Windows Live/Bing = 128.8 million (1:28:20)
5. YouTube = 128.1 (1:37:51)
6. Microsoft = 99.7 million (0:44:43)
7. Amazon = 87.9 million (0:42:10)
8. AOL Media Network = 84.0 million (2:51:19)
9. Apple = 79.1 million (1:08:28)
10. Wikipedia = 74.4 million (0:17:36)

In December 2011, Amazon rose up the charts in dramatic fashion while Ask Search Network dropped out of the top 10 list. It's important to point out that Amazon naturally sees a lift in traffic in December thanks to the holiday shopping season, so the brand's dramatic leap to 87.9 million in December 2011 is inflated for those holiday-related visitors. More interesting in these results is the fact that every brand saw an increase in traffic during 2011, but that's not the case for the amount of time individuals spent on each site.Every brand on the list saw an increase in time individuals spent on their sites between January 2011 and December 2011 except Facebook, which experienced a decrease in time spent on the site of approximately 33 minutes per person. Of course, Facebook does blow every other site on this list away in terms of the amount of time people spend on the site with nearly twice as much time or more spent on Facebook than any other site in the top 10. Clearly, Facebook is succeeding in keeping visitors engaged, but a 33 minute decrease in time spent on the site is a trend that should be raising some concerns at Facebook.These ten brands dominated the web among the U.S. internet audience in 2011 with nearly every brand enjoying steady growth in unique visitors and time on each site. That's not surprising given the steady growth in online internet usage overall in 2011. Take a look at the January 2011 and December 2011 metrics below to see what happened.

• Sessions/Visits per Person: January 2011 = 59; December 2011 = 62
• Domains Visited per Person: January 2011 = 99; December 2011 = 94
• Web Page Views per Person: January 2011 = 2,750; December 2011 = 2,803
• Duration of a Web Page Viewed: January 2011 = 0:00:58; December 2011 = 0:01:00
• Number of People Who Actively Went Online: January 2011 = 197.8 million; December 2011 = 211.9 million
• Number of People Who Had Internet Access: January 2011 = 243.0 million; December 2011 = 273.3 million

According to the numbers above, the number of people who had internet access grew by 12.5% between January 2011 and December 2011, but the number of people who actively went online during that time period only grew by 7.1%. The number of sessions per person went up by 5.1% in 2011. However, the number of web pages viewed per person only increased by 1.9% and the number of domains visited per person actually dropped by 1.9%.What do you think about the future of the top ten U.S. web brands and the continued growth of internet usage? Is there any chance for other brands to topple Google or Facebook? Leave a comment and share your thoughts.Image: stock.xchng