Table 2. Country characteristics and country income levels of the included studies.

Region	Number of studies
Asia	15
China		11	[25–35]
Taiwan		2	[17,36]
Cambodia		1	[38]
Thailand		1	[37]
Europe	11
Norway		3	[18,39,40]
Lithuania		1	[41]
Sweden		1	[19]
Italia		1	[42]
Ireland		1	[43]
Switzerland		2	[20,45]
United Kingdom		1	[21]
Multi-countries		1	[44]
North America	5
USA		4	[22,51–53]
Canada		1	[54]
Middle East	5
Iran		4	[46–49]
Saudi Arabia		1	[50]
Africa	3
Nigeria		3	[23,55,56]
Australia	1		[24]
Latin America	1		[57]
Country income level
High-income	18		[18–22,24,39–45,50–54]
Middle-income	23
Upper Middle-income		19	[17,25–37,46–49,57]
Lower Middle-income		4	[23,38, 55,56]
Low-income	0
Total	41