Where do referees reach for a card earliest?

Share of all cards shown in the opening fifteen minutes.

Super Liga (Serbia) reaches for a card earliest: 8.3% of its cards come in the first fifteen minutes.

Where do referees reach for a card earliest?
League	In first 15′	Cards
1. Super Liga Serbia	8.3%	1,172
2. Stars League Qatar	8.2%	527
3. Premier League Ukraine	8%	1,136
4. Ligat Ha'al Israel	7.8%	1,074
5. First League Russia	7.7%	1,475
6. K League 1 South Korea	7.5%	759
7. 1. SNL Slovenia	7.3%	826
8. Bundesliga Austria	7%	927
9. Liga Pro Ecuador	7%	1,309
10. Super League Uzbekistan	6.9%	231
11. Premyer Liqa Azerbaijan	6.9%	422
12. 2. Liga Austria	6.9%	1,255
13. K League 2 South Korea	6.8%	499
14. Pro League United Arab Emirates	6.8%	488
15. Liga I Romania	6.7%	1,414
16. Super League China	6.7%	957
17. La Liga Spain	6.6%	2,047
18. Copa Do Brasil Brazil	6.5%	596
19. Ligue 1 France	6.5%	1,121
20. Eredivisie Netherlands	6.5%	820
21. UEFA Champions League International	6.3%	945
22. HNL Croatia	6.3%	952
23. Super League Switzerland	6.3%	953
24. NB I Hungary	6.2%	995
25. Copa del Rey Spain	6.2%	515
26. Meistriliiga Estonia	6.1%	541
27. Serie A Italy	6.1%	2,050
28. Superliga Albania	6.1%	820
29. J2 League Japan	6.1%	759
30. Challenge League Switzerland	6%	848
31. Liga Profesional Argentina Argentina	6%	1,617
32. Premier League Egypt	6%	1,067
33. Allsvenskan Sweden	6%	872
34. Taça de Portugal Portugal	6%	252
35. Division Profesional - Clausura Paraguay	5.9%	674
36. Premijer Liga Bosnia & Herzegovina	5.9%	561
37. Primera A Colombia	5.8%	2,838
38. Ekstraklasa Poland	5.8%	1,300
39. Premier League Russia	5.8%	1,344
40. 1. Division Cyprus	5.8%	622

Showing every competition. Major competitions only

Regular time only. Across the majors it is 5.3%.