An independent report released last week indicated that the number of visitors to Wikipedia had nearly quadrupled during the past year. It also included a variety of information that helps to place Wikipedia's growth in perspective.

The report was released on Thursday by Nielsen//NetRatings, an arm of the firm that conducts the television Nielsen ratings. An accompanying press release focused on websites it classified in the "educational reference" category, which it indicated had grown by 22% from September 2004 to September 2005. It identified Wikipedia as the fastest-growing site in the category, with a 289% increase in the number of unique visitors over that period.

While such figures are often the result of starting from a small base number, which can produce high percentages on modest growth, this is not the case for Wikipedia. In fact, Wikipedia has established itself as a leading reference site, as indicated in an earlier report from Hitwise (see archived story). Already as of a year ago, based on the Nielsen report, Wikipedia's audience was larger than the current audience of the second fastest-growing site in the category, Yahoo! Education.

The report noted that most of the growth in the category could be attributed to these two sites, and in fact Wikipedia could potentially account for all of it on its own. Even considered in terms of raw numbers rather than percentages, growth in number of unique visitors to Wikipedia was larger than that of the category as a whole. In September 2004, Wikipedia had 3.3 million unique visitors, which grew to 12.8 million for September 2005, a difference of 9.5 million in the US. Overall, the number of unique visitors for the educational reference category increased by only 8.5 million in the same period.

According to the report, the growth means that sites in the category are reaching 31% of those using the internet. Extrapolating from this, the statistics provided would indicate that Wikipedia reached 8.5% of all internet users during September 2005. As a point of reference, similar numbers from Alexa (calculated on a daily basis) indicate that just over 1% of internet users visit Wikipedia on any given day.

In a sense, Wikipedia actually occupies two places on the list. The tenth fastest-growing site on the list is NationMaster, which has been using Wikipedia content for its encyclopedia for over two years (the site also provides other data about countries taken from different sources). Also worth mentioning is that the third fastest-growing site, the how-to site eHow, has its own wiki (called wikiHow) with content available under a Creative Commons license. WikiHow uses a modified version of the MediaWiki software and has a level of activity approximately equal to the English Wikibooks.

Also emphasized in the report was demographic information for the category, indicating that 63% of those visiting educational reference sites were age 35 or older. This contrasts with the commonly held view that Wikipedia editors tend to be younger, such as college students for example. In terms of education, however, the report did indicate that nearly half of those using educational reference sites had a college degree. Demographic information for individual sites was not included in the material released to the public.

Source: Nielsen//NetRatings - Press Release