Top nations in physics

	Country	Papers	Citations	Citations per paper
1	Switzerland	20,643	316,939	15.35
2	Denmark	7,183	101,677	14.16
3	United States	205,678	2,887,903	14.04
4	Austria	8,721	122,360	14.03
5	The Netherlands	16,311	224,541	13.77
6	England	51,861	638,497	12.31
7	Germany	97,673	1,178,343	12.06
8	Israel	13,084	155,999	11.92
9	Canada	24,538	3,969	11.17
10	Sweden	14,536	161,753	11.13
11	Spain	28,487	308,265	10.82
12	France	70,481	738,285	10.47
13	Italy	47,775	486,026	10.17
14%3D	Belgium	11,987	118,439	9.88
14%3D	Australia	14,621	144,406	9.88
16	Japan	109,893	953,821	8.68
17	Poland	24,647	186,321	7.56
18	Brazil	19,933	141,730	7.11
19	South Korea	35,541	246,652	6.94
20	India	29,984	198,639	6.62

The data above were extracted from the Essential Science Indicators database of Thomson Reuters. This database, currently covering the period January 1999 through October 2009, surveys only journal articles (original research reports and review articles) indexed by Thomson Reuters. Articles are assigned to a category based on the journals in which they were published and the Thomson Reuters journal-to-category field-definition scheme. Both articles tabulated and citation counts to those articles are for the period indicated.

Here our ranking in physics is by citations per paper – among nations that collected 100,000 or more citations during the period – to reveal weighted impact. For articles with multiple authors from different nations, each nation receives full, not fractional, citation credit. Essential Science Indicators lists nations ranked in the top 50 per cent for a field over a given period, based on total citations. In physics, 88 nations are listed, meaning 176 were surveyed. Twenty-three nations collected at least 100,000 citations in this field during the period.

A comparison of this survey with a similar one from two years ago shows few meaningful changes in rank order by impact. However, England has moved up in the latest survey from eighth to sixth. Also, Russia has dropped out of the top 20 and India entered it, comparing 1997-2007 with 1999-2009.

For more information on Thomson Reuters Essential Science Indicators, see http://scientific.thomsonreuters.com/products/esi.