| Year Joined | Answer | % Correct |
|---|---|---|
| 1949 | Denmark | 100%
|
| 1949 | France | 100%
|
| 1955 | Germany | 100%
|
| 1982 | Spain | 100%
|
| 1949 | United Kingdom | 100%
|
| 2009 | Croatia | 97%
|
| 1952 | Greece | 97%
|
| 1949 | Italy | 97%
|
| 1949 | Norway | 97%
|
| 1999 | Poland | 97%
|
| 1949 | Portugal | 97%
|
| 2004 | Bulgaria | 95%
|
| 1999 | Czech Republic | 95%
|
| 1949 | Iceland | 95%
|
| 2004 | Slovakia | 95%
|
| 2004 | Slovenia | 95%
|
| 1949 | United States | 95%
|
| 1949 | Belgium | 92%
|
| 2004 | Estonia | 92%
|
| 1999 | Hungary | 92%
|
| 2004 | Latvia | 92%
|
| 1949 | Netherlands | 92%
|
| 1952 | Turkey | 92%
|
| 2009 | Albania | 90%
|
| 1949 | Canada | 90%
|
| 2004 | Lithuania | 90%
|
| 2004 | Romania | 90%
|
| 1949 | Luxembourg | 87%
|
| 2017 | Montenegro | 79%
|