Table 1. Extracted data from the systematic review of Garner et al. ⁹ .

Data is reproduced under the terms of the Creative Commons Attribution Non Commercial (CC BY-NC 4.0).

Study	Year	Country	City	Latitude	Sample size	Mean age	Mean RP frequency
Brand	1997	USA	Boston	42.36	4182	51.8	7.20
Fraenkel	1999	USA	Boston	42.36	1525	53.9	7.80
Harada	1991	Japan	Ehime	33.84	3873	20–70	1.60
Ivorra	2001	Spain	Valencia	39.47	276	54.4	3.30
Maricq	1997	USA	South Carolina	33.84	2518	>18	2.10
Maricq	1997	France	Toulon	43.12	2187	>18	7.10
Maricq	1997	France	Nyons	44.36	2341	>18	6.00
Maricq	1997	France	Grenoble	45.19	2341	>18	9.25
Maricq	1997	France	Tarentaise	45.37	2296	>18	11.05
Onbasi	2005	Turkey	Van	38.50	768	29.2	5.90
Heslop	1983	UK	Southampton	50.91	450	20–59	12.70
Purdie	2009	New Zealand	Wellington	41.25	234	>18	11.50
Sahin	2003	Turkey	Van	38.50	251	28.9	3.98
Leppert	1987	Sweden	Vasteras	59.61	2705	18–59	11.00
Olsen	1978	Denmark	Copenhagen	55.68	67	21–50	15.51
Tzilalis	2011	Greece	Athens	37.98	3912	18–28	0.31
Cakir	2008	Turkey	Edirne	41.15	1414	27.2	3.60
Gallo	1994	Italy	Milan	45.46	1920	15–84	4.20
Voulgari	2000	Greece	Ioannina	39.77	500	33.7	5.20
Jones	2003	UK	Manchester	53.48	716	12–15	14.90