Task: Question Generation
Input (English): The Greek national football team, ranking 12th in the world in 2014 (and having reached a high of 8th in the world in 2008 and 2011), were crowned European Champions in Euro 2004 in one of the biggest upsets in the history of the sport and became one of the most successful national teams in European football, being one of only nine national teams to have won the UEFA European Championship. The Greek Super League is the highest professional football league in the country comprising eighteen teams. The most successful are Olympiacos, Panathinaikos, AEK Athens and PAOK.
Output (English): How many national teams have won the UEFA European Championship?