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Table representation of search results timeline featuring number of search results per year.
Year
Number of Results
1963
3
1964
6
1965
12
1966
103
1967
283
1968
441
1969
460
1970
435
1971
513
1972
538
1973
555
1974
515
1975
450
1976
385
1977
385
1978
311
1979
339
1980
277
1981
294
1982
294
1983
272
1984
299
1985
261
1986
277
1987
262
1988
253
1989
257
1990
279
1991
316
1992
274
1993
299
1994
252
1995
266
1996
278
1997
276
1998
284
1999
302
2000
290
2001
306
2002
376
2003
347
2004
321
2005
347
2006
360
2007
316
2008
356
2009
320
2010
298
2011
298
2012
311
2013
290
2014
282
2015
262
2016
223
2017
190
2018
158
2019
169
2020
155
2021
78
2022
11
2023
4
2024
30
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Adaptive Clinical Trial
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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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