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 | 2008 | 35 |
| Non-citable documents | 2009 | 80 |
| Non-citable documents | 2010 | 104 |
| Non-citable documents | 2011 | 122 |
| Non-citable documents | 2012 | 189 |
| Non-citable documents | 2013 | 277 |
| Non-citable documents | 2014 | 267 |
| Non-citable documents | 2015 | 341 |
| Non-citable documents | 2016 | 358 |
| Citable documents | 2008 | 146 |
| Citable documents | 2009 | 292 |
| Citable documents | 2010 | 463 |
| Citable documents | 2011 | 486 |
| Citable documents | 2012 | 454 |
| Citable documents | 2013 | 361 |
| Citable documents | 2014 | 230 |
| Citable documents | 2015 | 212 |
| Citable documents | 2016 | 209 |