Changes in the Structures and Directions of Rock Excavation Research from 1999 to 2020: A Bibliometric Study

Table 1

Top 20 research countries.

Serial number	Country	Documents	Citations	Number of citations per article
1	China	1836	23138	12.60
2	USA	517	13384	25.89
3	Australia	311	5633	18.11
4	Canada	303	8890	29.34
5	France	247	5775	23.38
6	Turkey	198	3961	20.01
7	Italy	185	2971	16.06
8	Germany	166	3009	18.13
9	Iran	163	2552	15.66
10	England	153	3421	22.36
11	Japan	150	3610	24.07
12	Spain	137	2313	16.88
13	Switzerland	133	3774	28.38
14	South Korea	113	2038	18.04
15	India	104	1412	13.58
16	South Africa	99	2096	21.17
17	Poland	90	662	7.36
18	Sweden	73	2058	28.19
19	Norway	62	1627	26.24
20	Russia	59	1089	18.46