As of June 2008, only 59.1% percent of Internet users worldwide use the latest major version of their preferred web browser. Firefox users are the most attentive: 92.2% of them surfed with Firefox 2. Only 52.5% of Microsoft Internet Explorer users have updated to version 7, which is the most secure according to multiple publicly-cited Microsoft experts. Users are vulnerable to exploitation due to their web browser’s “built-in” vulnerabilities and the lack of more recent security mechanisms such as improved phishing protection.”]
Source: https://security.googleblog.com/2008/07/are-you-using-latest-web-browser.html