It's been a little bit more than two years now since Google merged Google Spreadsheets with Writely, and while there has been a lot of talk about online office suites, the latest data from Compete indicates that Google Docs & Spreadsheets is still mostly attracting casual users who don't spend a lot of time with the service. Also, one of the most interesting data points in the Compete study is that only about 58% of unique visitors to Docs & Spreadsheets actually used one of the available apps after visiting the site. A large number of users never makes it past the marketing pages.

Overall, traffic to Google Docs grew 158% in the past 12 months. In September 2008, Docs & Spreadsheets reached around 4.4 million users. This, according to Compete, represents 2.4% of the U.S. adult online population.

Compete also compiled engagement metrics for Google Docs, which clearly indicate that the service is still mostly popular with casual users. The average user uses Google Docs about 3 times a month, a number that has held stable for the last 12 months. Interestingly, the average user only spends about 5 minutes per month on the site.

Zoho

Compete also provided us with some additional data about Zoho's office suite, one of Google Docs closest competitors. Zoho saw about 310,000 unique visitors in October, but those users spent close to 10 minutes per month on the service. While this is twice the amount of time users spent on Google Docs, Zoho's users also visit the site about 3 times a month.

Update: We also received some additional information from ClickStream Technologies . ClickStream's survey compares usage numbers for Google Docs, OpenOffice, and Microsoft Word. The results of this survey are very similar to Compete's statistics, both with regards to how often the apps were used and for how long.

Casual Users

Google Docs clearly still mostly attracts casual users. Those users who spend most of their days in word processors and spreadsheets have not switched over to web based productivity applications. About a year ago, we wrote that Google Docs wasn't ready for the enterprise, and this data from Compete shows that, a year later, it still hasn't been adopted by power users (though the Compete study did not look at enterprise and business users, who would be running Google Apps on their own domain).