Table A1.
This shows the primary source of the 2146 included articles. 18 articles were from special issues, 5 were found accidentally, 1 was from a review and 1 was from a colleague. Many articles were found using multiple methods. The papers listed here in the GS column were not found by PM but may also have been identified by CB. Abbreviations: PM = PubMed, GS = Google Scholar, CB = Colin Butler.
| Year | PM | GS | BMJ | Other | CB | Total |
|---|---|---|---|---|---|---|
| 1989 | 2 | 1 | 3 | |||
| 1990 | 2 | 3 | 2 | 7 | ||
| 1991 | 14 | 1 | 15 | |||
| 1992 | 1 | 8 | 2 | 11 | ||
| 1993 | 7 | 7 | 14 | |||
| 1994 | 11 | 11 | 22 | |||
| 1995 | 13 | 17 | 1 | 31 | ||
| 1996 | 12 | 18 | 30 | |||
| 1997 | 16 | 21 | 37 | |||
| 1998 | 15 | 17 | 1 | 1 | 34 | |
| 1999 | 10 | 19 | 29 | |||
| 2000 | 30 | 16 | 1 | 1 | 3 | 51 |
| 2001 | 34 | 8 | 2 | 1 | 45 | |
| 2002 | 28 | 8 | 1 | 1 | 38 | |
| 2003 | 17 | 8 | 1 | 1 | 27 | |
| 2004 | 29 | 12 | 2 | 43 | ||
| 2005 | 35 | 18 | 4 | 2 | 59 | |
| 2006 | 55 | 11 | 2 | 68 | ||
| 2007 | 67 | 16 | 3 | 3 | 89 | |
| 2008 | 134 | 22 | 7 | 1 | 1 | 164 |
| 2009 | 109 | 54 | 18 | 1 | 2 | 184 |
| 2010 | 186 | 106 | 6 | 14 | 2 | 314 |
| 2011 | 176 | 93 | 5 | 1 | 275 | |
| 2012 | 158 | 108 | 2 | 1 | 269 | |
| 2013 | 154 | 126 | 2 | 2 | 284 | |
| Total | 1313 | 730 | 58 | 25 | 17 | 2143 |