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Table representation of search results timeline featuring number of search results per year.
Year
Number of Results
1964
1
1965
22
1966
45
1967
45
1968
44
1969
39
1970
37
1971
35
1972
28
1973
58
1974
48
1975
61
1976
33
1977
35
1978
31
1979
36
1980
46
1981
49
1982
56
1983
47
1984
73
1985
48
1986
43
1987
43
1988
58
1989
42
1990
40
1991
36
1992
39
1993
34
1994
32
1995
25
1996
20
1997
28
1998
26
1999
18
2000
24
2001
22
2002
26
2003
28
2004
17
2005
25
2006
29
2007
55
2008
33
2009
30
2010
38
2011
33
2012
35
2013
24
2014
29
2015
37
2016
36
2017
27
2018
33
2019
23
2020
26
2021
12
2024
4
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MLA
NLM
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AMA
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Adaptive Clinical Trial
Address
Autobiography
Bibliography
Biography
Case Reports
Classical Article
Clinical Conference
Clinical Study
Clinical Trial Protocol
Clinical Trial, Phase I
Clinical Trial, Phase II
Clinical Trial, Phase III
Clinical Trial, Phase IV
Clinical Trial, Veterinary
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Comparative Study
Congress
Consensus Development Conference
Consensus Development Conference, NIH
Controlled Clinical Trial
Corrected and Republished Article
Dataset
Dictionary
Directory
Duplicate Publication
Editorial
Electronic Supplementary Materials
English Abstract
Equivalence Trial
Evaluation Study
Expression of Concern
Festschrift
Government Publication
Guideline
Historical Article
Interactive Tutorial
Interview
Introductory Journal Article
Lecture
Legal Case
Legislation
Letter
Multicenter Study
News
Newspaper Article
Observational Study
Observational Study, Veterinary
Overall
Patient Education Handout
Periodical Index
Personal Narrative
Portrait
Practice Guideline
Pragmatic Clinical Trial
Preprint
Published Erratum
Randomized Controlled Trial, Veterinary
Research Support, American Recovery and Reinvestment Act
Research Support, N.I.H., Extramural
Research Support, N.I.H., Intramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.
Research Support, U.S. Gov't
Retracted Publication
Retraction of Publication
Scientific Integrity Review
Technical Report
Twin Study
Validation Study
Video-Audio Media
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