Not every article in a journal is considered primary research and therefore "citable", this chart shows the ratio of a journal's articles including substantial research (research articles, conference papers and reviews) in three year windows vs. those documents other than research articles, reviews and conference papers.
| Documents | Year | Value |
| Non-citable documents | 2004 | 1 |
| Non-citable documents | 2005 | 1 |
| Non-citable documents | 2006 | 2 |
| Non-citable documents | 2007 | 2 |
| Non-citable documents | 2008 | 3 |
| Non-citable documents | 2009 | 4 |
| Non-citable documents | 2010 | 5 |
| Non-citable documents | 2011 | 6 |
| Non-citable documents | 2012 | 6 |
| Non-citable documents | 2013 | 7 |
| Non-citable documents | 2014 | 8 |
| Non-citable documents | 2015 | 9 |
| Non-citable documents | 2016 | 9 |
| Citable documents | 2004 | 33 |
| Citable documents | 2005 | 33 |
| Citable documents | 2006 | 69 |
| Citable documents | 2007 | 70 |
| Citable documents | 2008 | 109 |
| Citable documents | 2009 | 104 |
| Citable documents | 2010 | 111 |
| Citable documents | 2011 | 119 |
| Citable documents | 2012 | 130 |
| Citable documents | 2013 | 134 |
| Citable documents | 2014 | 129 |
| Citable documents | 2015 | 129 |
| Citable documents | 2016 | 127 |