Table 1.

Country/region and number of published articles.

Country/Region	No. of Articles	Percentage	Frequency of Citations	Centrality	Year of First Publication
USA	1088	31.555%	1010	0.36	1997
Italy	333	9.658%	262	0.17	2000
Canada	235	6.816%	205	0.16	2003
Spain	234	6.787%	185	0.21	2007
People’s R. China	209	6.061%	162	0.09	2012
South Korea	200	5.800%	155	0.09	2003
England	193	5.597%	148	0.1	2001
Australia	136	3.944%	97	0.2	2007
Brazil	135	3.915%	103	0.06	2013
Netherlands	135	3.915%	104	0.16	2008