| Domain | No. of articles |
| 1997 | 1 |
| 2001 | 1 |
| 2004 | 1 |
| 2005 | 2 |
| 2006 | 1 |
| 2007 | 3 |
| 2008 | 3 |
| 2009 | 4 |
| 2010 | 4 |
| 2011 | 3 |
| 2012 | 4 |
| 2013 | 12 |
| 2014 | 6 |
| 2015 | 5 |