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Table 1 The top 10 ranking of the most productive countries in publishing the largest number of articles associated with khat during the period from 1952 to 2014

From: Bibliometric analysis on global Catha edulis (khat) research production during the period of 1952–2014

SCR

Countries

No. of articles (%)

h-index

Median (Q1-Q3) of citation

Average of citation

Collaborations with foreign countries

Number (%)a of documents with international authors

Adjustment index b

1st

UK

99 (15.2)

22

7 (2–20)

15.2

13

27 (27.3)

2.4

2nd

Yemen

67 (10.3)

17

4 (0.0-21)

12.9

19

45 (67.2)

45.5

3rd

USA

63 (9.7)

15

5 (1–4)

10.7

10

25 (39.7)

1.2

4th

Ethiopia

59 (9.1)

12

1 (0.0-11)

7.9

16

20 (33.9)

116.8

5th

KSA

55 (8.4)

11

2 (1–9)

6.4

11

16 (29.1)

2.1

6th

Switzerland

47 (7.2)

17

10 (2–33)

22.6

1

4 (8.5)

0.6

7th

Germany

32 (4.9)

12

9 (1–24)

15.8

15

17 (53.1)

0.7

8th

Kenya

23 (3.5)

10

8 (4–15)

11.3

3

6 (26.1)

18.5

9th

Egypt

20 (3.1)

5

1 (0–5.8)

3.1

7

12 (60.0)

6

10th

Italy

19 (2.9)

11

16 (5–28)

18.3

6

4 (21.1)

0.5

  1. KSA The Kingdom of Saudi Arabia, SCR Standard Competition Ranking, USA The United States of America, UK The United Kingdom, Q1–Q3 lower quartile - upper quartile
  2. aPercentage of documents with international authors from the total number of documents for each country
  3. bAn adjustment index (AI) was measured using the following formula: AI = [total number of publications for the country / GDP per capita of the country]*1,000, where GDP per capita = GDP/population of the country