Table 2.

Country of origin from included studies (N=18).

Country of origin	Count, n (%)	References
United States	10 (56)	[21,22,24,26-32]
Australia	2 (11)	[33,34]
Other (Canada, France, the Netherlands, Oman, Sweden, and United Kingdom)	6 (33)	[23,25,35-38]