| Country | Year Joined | % Correct |
|---|---|---|
| United States | 1949 | 91%
|
| Canada | 1949 | 86%
|
| Denmark | 1949 | 86%
|
| France | 1949 | 86%
|
| Norway | 1949 | 86%
|
| Poland | 1999 | 86%
|
| United Kingdom | 1949 | 86%
|
| Belgium | 1949 | 82%
|
| Portugal | 1949 | 82%
|
| Romania | 2004 | 82%
|
| Bulgaria | 2004 | 77%
|
| Croatia | 2009 | 77%
|
| Czech Republic | 1999 | 77%
|
| Estonia | 2004 | 77%
|
| Greece | 1952 | 77%
|
| Hungary | 1999 | 77%
|
| Latvia | 2004 | 77%
|
| Lithuania | 2004 | 77%
|
| Luxembourg | 1949 | 77%
|
| Spain | 1982 | 77%
|
| Turkey | 1952 | 77%
|
| Italy | 1949 | 73%
|
| Netherlands | 1949 | 73%
|
| Slovakia | 2004 | 68%
|
| Iceland | 1949 | 64%
|
| Slovenia | 2004 | 64%
|
| Albania | 2009 | 55%
|
| Montenegro | 2017 | 55%
|
| North Macedonia | 2020 | 55%
|
| West Germany | 1955 | 45%
|
| East Germany | 1990 | 41%
|