IE6, the notoriously security plagued version, is the browser of choice for one in five employees. IE6 use dropped nearly 10% in the first two quarters of 2010 and continues to decline. Almost three quarters of the Web traffic the company monitors was viewed on versions of Internet Explorer, compared to estimates of around 60% market share in the population at large. IE 6 has been a common element in many high profile security incidents, such as the Google Aurora attacks at the end of 2009 relied, in part, on an exploit of a previously unknown IE vulnerability.
Source: https://threatpost.com/old-and-insecure-ie6-still-popular-enterprise-081810/74351/