Ask HN: why does the TIOBE index omit HaXe, CoffeeScript and Vala?

Neither CoffeeScript nor HaXe or Vala figure in the 2013 TIOBE index [1]. If I had to guess I'd say all of them are more widely used than most included in the >50 group, and the index does feature "transpiled" languages like Dart and Fantom.

They claim to use search engines and other web resources to compile the listing, what could account for these missing? Are they really less common than Dart, Eiffel, Gambas, Dylan, etc?

[1] http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html