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 | 1999 | 14 |
| Non-citable documents | 2008 | 10 |
| Non-citable documents | 2009 | 21 |
| Non-citable documents | 2010 | 26 |
| Non-citable documents | 2011 | 31 |
| Non-citable documents | 2012 | 54 |
| Non-citable documents | 2013 | 69 |
| Non-citable documents | 2014 | 81 |
| Non-citable documents | 2015 | 84 |
| Non-citable documents | 2016 | 108 |
| Citable documents | 1999 | 27 |
| Citable documents | 2008 | 161 |
| Citable documents | 2009 | 311 |
| Citable documents | 2010 | 437 |
| Citable documents | 2011 | 396 |
| Citable documents | 2012 | 380 |
| Citable documents | 2013 | 392 |
| Citable documents | 2014 | 386 |
| Citable documents | 2015 | 375 |
| Citable documents | 2016 | 375 |