| countries | Date | % Correct |
|---|---|---|
| France, Italy, West Germany, Belgium, Netherlands and Luxembourg | 1957 | 100%
|
| United Kingdom, Irland and Denmark | 1973 | 100%
|
| Greece | 1981 | 100%
|
| Spain and Portugal | 1986 | 100%
|
| Austria, Suede and Finland | 1995 | 100%
|
| Estonia, Latvia, Lithuania, Poland, Czech Republic,Slovakia, Hungary and Slovenia | 2004 | 100%
|
| Roumania and Bulgaria | 2007 | 100%
|
| Croatia | 2013 | 100%
|
| Brexit | 2020 | 100%
|