Caption: This network graph shows all the collaborative relations between countries. Those shown on this graph have published at least 15 joint Medline scientific articles with another country. Each country is represented by a circle, the diameter and size of which are proportional to the number of publications during the period. Coloured clusters represent countries who publish more frequently together. A shorter distance between countries and a thicker line connecting the circles indicate greater collaboration between countries.

Source: publication sources from Pubmed. Analysis tool with Vos Viewer software