Table 1.

Dispersions of author collaboration across continents over the years

Continent, Country		2013	2014	2015	2016	2017	2018	Total, n (%)	Growtha	x-index
Africa		—b	2	1	2	2	1	8 (1.18)	0.71	—
	Kenya	—	—	1	—	—	—	1 (0.15)	—	1.95
	Nigeria	—	—	—	—	1	—	1 (0.15)	0.71	—
	South Africa	—	2	—	2	1	—	5 (0.74)	0.32	2.42
	Uganda	—	—	—	—	—	1	1 (0.15)	—	—
Asia		3	10	8	9	22	32	84 (12.43)	0.83	—
	China	2	2	1	1	7	12	25 (3.7)	0.57	3.19
	South Korea	—	—	2	2	4	6	14 (2.07)	0.94	3.08
	Singapore	—	3	—	—	1	4	8 (1.18)	–0.12	3.56
	Thailand	—	2	2	—	1	2	7 (1.04)	—	2.25
	Taiwan	—	—	—	1	2	3	6 (0.89)	0.88	1.39
	Others	1	3	3	5	7	5	24 (3.55)	0.97	—
Europe		15	12	18	35	60	67	207 (30.62)	0.89	—
	United Kingdom	2	—	9	9	13	12	45 (6.66)	0.91	6.65
	Germany	2	2	1	2	11	11	29 (4.29)	0.68	5.97
	Spain	5	1	1	4	5	10	26 (3.85)	0.23	5.41
	Netherlands	1	—	1	9	7	6	24 (3.55)	0.81	4.7
	Sweden	—	3	4	4	3	4	18 (2.66)	0.67	4.84
	Others	5	6	2	7	21	24	65 (9.62)	0.71	—
North America		6	21	52	70	90	54	293 (43.34)	0.99	—
	United States	6	17	42	58	79	47	249 (36.83)	0.99	17.13
	Canada	—	4	10	12	11	7	44 (6.51)	0.92	8.74
Oceania		1	9	15	21	19	11	76 (11.24)	0.93	—
	Australia	1	8	13	17	15	10	64 (9.47)	0.91	11.03
	New Zealand	—	1	2	4	4	1	12 (1.78)	0.97	4.81
South America		—	3	1	—	3	1	8 (1.18)	0.31	—
	Brazil	—	2	—	—	2	1	5 (0.74)	0.29	2.52
	Colombia	—	1	—	—	—	—	1 (0.15)	–0.35	1.59
	Peru	—	—	1	—	1	—	2 (0.3)	0.58	1.59
Total		25	57	95	137	196	166	676 (100)	0.99	26.56

^aGrowth based on data from 2013 and 2017.

^bNot applicable.