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Key MEDLINE® Indicators Archive: FY1996-1999

  FY1999 % Change FY1998 % Change FY199715 % Change FY199615
Citations Indexed for MEDLINE 434,000 +5% 411,921 -21% 519,012 +38% 322,825
MEDLINE/PubMed® Searches16 ---- --- --- --- --- --- ---
Journal Titles in MEDLINE 4,007 +2% 3,942 +2% 3,879 <+1% 3,868
Journal Titles in
Index Medicus7
3,378 +2% 3,302 +3% 3,211 <+1% 3,200
Total Citation Data Creation 453,000 +4% 434,000 -13% 496,000 +33% 336,000

Keyboarded Citations13

198,000 -24% 260,000 -41% 434,000 +23% 336,000

OCRed Citations8

151,000 +16% 130,000 +53% 62,000 --- 0

Citations Received
Electronically via XML9

104,000 +136% 44,000 --- 0 --- 0
Retraction Notices10 33 -38% 53 +112% 25 +56% 16
Retracted Articles10 ---- ---- ---- ---- ---- ---- ----
Errata10 2,848 -42% 4,953 +40% 3,526 +245% 1,021
Comments10 16,270 -4% 16,867 -46% 30,986 +48% 20,952

See also additional MEDLINE statisitics.

Current Years
Prior Years:

The U.S. Government Fiscal Year (FY) runs from October 1 - September 30.

Not all footnotes apply to archived years.

1Statistical gathering method changed effective with April 2003 data.
2Includes Internet Grateful Med® searches totaling about 27 million.
3NLM Gateway was released to the public on October 16, 2000 but the statistics include only April-September 2001 usage.
4The net increase of one journal resulted from the deselection of nearly 250 nursing and dental journals that had not been indexed for several years and the addition of about 50 titles from the former SPACELINE, HISTLINE®, and BIOETHICSLINE® databases. These journals were not included in IM.
5About 40 titles of the increase were due to the addition of former AIDSLINE® titles.
6Re: FY2000 - About half of the 325 title increase was due to the addition of former HealthSTAR titles. The remainder are new titles.
7Index Medicus® (ceased in print after December 2004 issue) was a monthly bibliographic listing of current biomedical references derived from MEDLINE. Included: subject and author sections and separate Bibliography of Medical Reviews. Remains an online indicator in MEDLINE citations found in PubMed.
8Optical Character Recognition after scanning.
9eXtensible Markup Language
10See Errata, Retractions, and Other Linked Citations in PubMed for definitions. NLM began to report retracted articles separately in FY2003. Prior to that the numbers reported were Retraction Notices only.
11No maintenance was done on comments and errata from October 2000 - April 2001 as the new maintenance system was being developed and tested.
12Includes revised and re-edited comments entered in previous years.
13Keyboarding ceased as a method of data entry in June 2004.
14Numbers are coincidentally the same; there were 3 notices published twice (retracting the same publications) while there were some notices retracting multiple articles.
15There was a data entry and concomitant indexing backlog resulting from the General Services Administration Board of Contract Appeals' suspension of NLM editing and data entry contract from late February 1996 to late April 1996. The large backlog was eliminated in early April 1997. This caused fewer records to be added to MEDLINE during FY1996 and a greater number added in FY1997.
16For comparison, ELHILL® (mainframe computer retrieval software for MEDLINE and other NLM databases) searches were 7,397,000 in FY1996; 8,741,000 in FY1997; 15,600,000 in FY1998; and dropped to about 3,000,000 in FY1999 when ELHILL ceased Sept. 30, 1999 for direct searching. That drop is attributed to the main search access having shifted to PubMed (including IGM, Internet Grateful Med) which was estimated to be 220 million searches for FY1999.
17June 2007 implementation of Entrez 2.0 ("portals") resulted in changes to the statistical gathering process. FY2008 represents a new baseline for the data and cannot be compared to FY2007.
18Statistical gathering method was enhanced effective October 2006 to collect previously unreported access.
19Includes about 110 history of medicine journals and 13 bioethics journals.
20NLM began to report partial retractions separately in December 2006.

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