What 6 countries joined the European Union after 1973?

As of 2015, 19 new countries have joined what is now the European Union, since 1973.

1981: Greece.

1986: Spain and Portugal.

1995: Sweden, Finland and Austria.

2004: Malta, Cyprus, Estonia, Latvia, Lithuania, Slovenia, Slovakia, Hungary, Poland and the Czech Republic.

2007: Bulgaria and Romania.

2013: Croatia.