Table 1 Worldwide growth of tramadol research activity
From: Worldwide research productivity on tramadol: a bibliometric analysis
Time interval | Number of published documents NÂ =Â 2059 | % |
|---|---|---|
2009–2013 | 778 | 37.79 |
2004–2008 | 586 | 28.46 |
2003–1999 | 383 | 18.6 |
1994–1998 | 198 | 9.62 |
1989–1993 | 63 | 3.06 |
<1989 | 51 | 2.48 |