Table 1.

Number of original research articles with authors given equal credit and annual prevalence

Year	NEJMa	JAMAb	Annalsc	Lancet	BMJd
2000	3/362 (<1%)	0/349 (0%)	0/200 (0%)	4/795 (<1%)	0/579 (0%)
2001	1/362 (<1%)	1/364 (<1%)	1/204 (<1%)	7/716 (1.0%)	1/586 (<1%)
2002	7/372 (1.9%)	8/357 (2.2%)	0/176 (0%)	16/637 (2.5%)	3/590 (<1%)
2003	20/361 (5.5%)	5/372 (1.3%)	1/196 (<1%)	21/531 (4.0%)	1/643) (<1%)
2004	11/299 (3.7%)	5/340 (1.5%)	5/180 (2.8%)	18/498 (3.6%)	1/623 (<1%)
2005	20/306 (6.5%)	5/307 (1.6%)	5/178 (2.8%)	15/396 (3.8%)	4/514 (<1%)
2006	19/283 (6.7%)	9/257 (3.5%)	3/159 (1.9%)	10/330 (3.0%)	3/333 (<1%)
2007	17/338 (5.0%)	10/229 (4.4%)	3/158 (1.9%)	13/326 (4.0%)	1/292 (<1%)
2008	19/328 (5.8%)	9/211 (4.3%)	4/156 (2.6%)	18/311 (5.8%)	4/260 (1.5%)
2009	29/336 (8.6%)	17/226 (7.5%)	7/186 (3.8%)	10/279 (3.6%)	5/525 (1.0%)
Total	146/3347 (4.4%)	69/3012 (2.3%)	29/1793 (1.6%)	132/4819 (2.7%)	23/4945 (<1%)
Trend	p < .001	p < .001	p < .001	p < .001	p < .001

^aNew England Journal of Medicine

^bJournal of the American Medical Association

^cAnnals of Internal Medicine

^dBritish Medical Journal