In October 2006 the combined unique visitors to Google Docs and Spreadsheets reached 445,762, with an average time spent of 10 minutes per visitor. This accounted for 92% of unique visitors and 95% of time spent among providers of Web-based productivity tools that month. Other providers include: EditGrid, Zoho.com, Thinkfree.com, Numsum.com and WriteBoard, among others. Since October 2006, growth at Google Docs and Spreadsheets has been relatively flat. In November 2006, these Google properties attracted 424,785 unique visitors and 432,156 unique visitors in December 2006. Time per visitor has increased somewhat, from an average of 10 minutes in October 2006 to 14 minutes in December 2006, Nielsen//NetRatings reports. Users of Google Docs and Spreadsheets skew toward higher incomes, with 28% of users earning upwards of $100,000 annually. A large majority of users, 76%, have an income greater than $50,000 annually.