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 | 27 |
| Non-citable documents | 2000 | 31 |
| Non-citable documents | 2001 | 36 |
| Non-citable documents | 2002 | 35 |
| Non-citable documents | 2003 | 20 |
| Non-citable documents | 2004 | 5 |
| Non-citable documents | 2005 | 5 |
| Non-citable documents | 2007 | 16 |
| Non-citable documents | 2008 | 14 |
| Non-citable documents | 2009 | 15 |
| Non-citable documents | 2010 | 13 |
| Non-citable documents | 2011 | 14 |
| Non-citable documents | 2012 | 14 |
| Non-citable documents | 2013 | 13 |
| Non-citable documents | 2014 | 10 |
| Non-citable documents | 2015 | 7 |
| Non-citable documents | 2016 | 5 |
| Non-citable documents | 2017 | 4 |
| Non-citable documents | 2018 | 4 |
| Non-citable documents | 2019 | 2 |
| Non-citable documents | 2020 | 3 |
| Non-citable documents | 2021 | 4 |
| Non-citable documents | 2022 | 4 |
| Citable documents | 1999 | 94 |
| Citable documents | 2000 | 87 |
| Citable documents | 2001 | 81 |
| Citable documents | 2002 | 61 |
| Citable documents | 2003 | 40 |
| Citable documents | 2004 | 26 |
| Citable documents | 2005 | 14 |
| Citable documents | 2007 | 9 |
| Citable documents | 2008 | 29 |
| Citable documents | 2009 | 49 |
| Citable documents | 2010 | 75 |
| Citable documents | 2011 | 80 |
| Citable documents | 2012 | 70 |
| Citable documents | 2013 | 61 |
| Citable documents | 2014 | 57 |
| Citable documents | 2015 | 61 |
| Citable documents | 2016 | 63 |
| Citable documents | 2017 | 62 |
| Citable documents | 2018 | 67 |
| Citable documents | 2019 | 71 |
| Citable documents | 2020 | 67 |
| Citable documents | 2021 | 64 |
| Citable documents | 2022 | 59 |