Drupal's Market Share
In 2009, the whitehouse.gov decided to migrate to Drupal Platform, and this was more of a confidence to many other government organizations to try out Drupal CMS, as the open source platform had now got the credibility that it deserved.
In the present world, with more than 150 federal government sites running on Drupal platform, it is kind of obvious that the Drupal CMS has an enormous market share when it comes to the government websites and the public sector in general. The list contains big guns like The White House, NASA, Department of Health, Department of Education, Transportation, Defense and the Homeland Security. When Drupal platform is being preferred by some of these big government sites, it is not surprising to see that many other private and media companies are inclining towards Drupal CMS for their own websites.