Table 2.

The top 10 countries/regions with the highest productivity.

Rank	Country/Region	Np	Percentage (%)	Tc	H-index
1	USA	4077	30.83	129206	139
2	CHINA	2354	17.80	45207	79
3	ENGLAND	937	7.09	41116	91
4	ITALY	718	5.43	25435	68
5	JAPAN	704	5.32	13833	52
6	GERMANY	700	5.29	24808	68
7	AUSTRALIA	689	5.21	34840	69
8	CANADA	629	4.76	22165	62
9	SOUTH KOREA	573	4.33	15840	42
10	INDIA	493	3.73	13563	51

NP = number of publication, TC = total citation.