Table 2.

General characteristics of selected articles

		Tobacco		Drug addiction		Alcohol
Characteristic	Category	Number	Percent	Number	Percent	Number	Percent
Total number of papers		4469	100	5403	100	2137	100
Year of publication	2013–2017	1688	37.8	2090	38.7	850	39.8
	2008–2012	1302	29.1	1565	29.0	536	25.1
	2003–2007	803	18.0	855	15.8	364	17.0
	1998–2002	364	8.1	489	9.1	234	10.9
	1993–1997	198	4.4	278	5.1	126	5.9
	1988–1992	82	1.8	70	1.3	24	1.1
	<  1988	32	0.7	57	1.0	3	0.1
Number of authors	1	286	6.4	418	7.8	166	7.8
	2–3	1300	29.1	1691	31.3	730	34.2
	4–6	1772	39.7	2197	40.7	866	40.5
	7–10	903	20.2	905	16.7	309	14.5
	> 10	208	4.7	192	3.6	66	3.1
Number of subject category	1	2261	50.6	2492	46.1	970	45.4
	2	1709	38.2	2331	43.1	934	43.7
	3	470	10.5	557	10.3	220	10.3
	4	22	0.5	14	0.3	9	0.4
	5	4	0.1	8	0.1	3	0.1
Country of first author (top 10) (number of papers)	1	USA	2464	USA	3329	USA	1444
	2	England	321	Australia	208	Australia	80
	3	Canada	179	England	200	England	76
	4	Australia	167	Canada	195	Canada	63
	5	Netherlands	99	Italy	115	Netherlands	40
	6	Spain	90	Germany	82	Sweden	33
	7	China	64	Spain	80	Italy	27
	8	Italy	60	France	77	Germany	26
	9	Germany	57	Netherlands	70	Iran	20
	10	Switzerland	57	Switzerland	61	Switzerland	18