Table 3.
Top 31 most frequent collaborating countries.
| From | To | Frequency |
|---|---|---|
| US | Canada | 132 |
| US | UK | 98 |
| US | Germany | 71 |
| UK | Canada | 66 |
| UK | Sweden | 62 |
| UK | Germany | 58 |
| US | China | 57 |
| US | Italy | 57 |
| The Netherlands | UK | 55 |
| US | Switzerland | 53 |
| UK | Italy | 50 |
| Italy | Germany | 49 |
| UK | Switzerland | 47 |
| The Netherlands | Germany | 42 |
| Sweden | Canada | 42 |
| Switzerland | Germany | 41 |
| US | Sweden | 41 |
| UK | Australia | 39 |
| US | The Netherlands | 39 |
| US | Denmark | 37 |
| Switzerland | France | 36 |
| UK | Norway | 36 |
| UK | France | 35 |
| US | France | 34 |
| Sweden | Switzerland | 33 |
| The Netherlands | Italy | 32 |
| US | Australia | 32 |
| Canada | Germany | 31 |
| France | Germany | 31 |
| Italy | Switzerland | 31 |
| UK | Denmark | 31 |