Several organizations survey the Internet, and report the characteristics of the browsers and displays they find. One is W3schools.com:
There are also services that will monitor visitors to your own site. If a Web site is of strategic importance to your organization, you will want to monitor it carefully, keeping track of the time users spend on the site, the frequency with which they view each page or section of the site, etc.The characterisitcs of visitors to my Web site at http://bpastudio.csudh.edu/fac/lpress/ during August 2008 are shown here.