Table 3.

Cited resource types by publication year periods

Publication year	Book No.	%	Gov No.	%	Int No.	%	Jour No.	%	Misc No.	%	All No.	%
2016–2018*	80	3.8%	1,838	28.5%	1,559	31.5%	3,948	10.8%	250	13.9%	7,675	14.8%
2010–2015	619	29.3%	3,243	50.3%	2,689	54.3%	17,229	47.3%	978	54.2%	24,758	47.8%
2004–2009	463	21.9%	618	9.6%	395	8.0%	8,538	23.4%	322	17.8%	10,336	20.0%
1994–2003	540	25.5%	344	5.3%	97	2.0%	4,987	13.7%	133	7.4%	6,101	11.8%
1984–1993	213	10.1%	45	0.7%	7	0.1%	1,146	3.1%	29	1.6%	1,440	2.8%
1974–1983	117	5.5%	11	0.2%	0	0.0%	385	1.1%	17	0.9%	530	1.0%
Pre-1974	81	3.8%	11	0.2%	0	0.0%	200	0.5%	40	2.2%	332	0.6%
No date	3	0.1%	337	5.2%	205	4.1%	5	0.0%	36	2.0%	586	1.1%
Total	2,116	100.0%	6,447	100.0%	4,952	100.0%	36,438	100.0%	1,805	100.0%	51,758	100.0%

^*Includes materials in press

Book = Books; Gov = Government documents; Int = Internet; Jour = Journals; Misc = Miscellaneous; All = All resource types