Browser Statistics are nonsense (Score 1)

The main reasons are:

• Text browsers and bots only load the (X)HTML file, no images or stylesheets. This results in only one file transfer, not maybe 10 or 20 when a graphical browser loads images etc. So non-graphical browsera are always undercountered
• Many Bots and the Opera Browser use the User Agent String from the Internet Explorer
• The graphical Browsers do have different caching and prefetching methods.

For more reasons you should read this article about the nonsense of browser statistics