Table 4.

Top 20 countries in terms of number of articles published.

No.	Frequency	Centrality	Institution
1	691	0.08	Peoples R China
2	351	0.18	USA
3	156	0.01	India
4	134	0.01	Turkey
5	91	0.01	Japan
6	74	0.24	England
7	61	0.02	Taiwan (Peoples R China)
8	59	0.1	Spain
9	56	0.2	Germany
10	56	0.01	South Korea
11	51	0.37	Italy
12	50	0.05	Poland
13	46	0.02	New Zealand
14	37	0.09	Sweden
15	34	0.01	Australia
16	30	0.02	Netherlands
17	27	0.01	Canada
18	25	0.01	Denmark
19	24	0.06	France
20	23	0.01	Pakistan