Firefox to US$7,500 cash reward) to researchers who discover severe security holes in Firefox. Official guidelines for handling security vulnerabilities discourage early disclosure of vulnerabilities so as not to give potential attackers an advantage in creating exploits. Because Firefox generally has fewer publicly known security vulnerabilities than Internet Explorer (see "Comparison of web browsers"), improved security is often cited as a reason to switch from Internet Explorer to Firefox. "The Washington Post" reported that exploit code for known critical security vulnerabilities in Internet Explorer was available for 284 days in 2006. In comparison, exploit code for known, critical security vulnerabilities in
Usage share of web browsers and Firefox (not included in Android). Chrome did not include the mobile numbers at that time while Android does since there was an "Android browser" that was the default browser at that time. 92% of sites monitored by StatOwl serve predominantly United States market. "AT Internet Institute" was formerly known as "XiTi". Method: Only counts visits to local sites in 23 European countries and then averages the percentages for those 23 European countries independent of population size. "TheCounter.com" identifies sixteen versions of six browsers (Internet Explorer, Firefox, Safari, Opera, Netscape, and Konqueror). Other browsers are categorised as either "Netscape compatible"