How many times in the history of the Champions League have three teams from the same country reached the semi-finals?

There have been five semi-finals in the history of the Champions League and three teams from the same country. The specific time and team name are as follows:

1, 1999/2000 season

Real Madrid, Valencia, Barcelona (both Spanish teams have reached the final), and the other team is Bayern Munich (Germany).

2.2002/2003 season

AC Milan, Juventus, Inter Milan (both Italian teams won the final), and the other team is Real Madrid (Spain).

3.2006/2007 season

Liverpool, Chelsea, Manchester United (all League One teams, champions AC Milan, Italy), and the other team is AC Milan (Italy).

4.2007/2008 season

Manchester United, Chelsea, Liverpool (both English teams have reached the final), and the other team is Barcelona (Spain).

5.2008/2009 season

Manchester United, Chelsea, Arsenal (all League One teams, the champions are Barcelona, Spain), and the other team is Barcelona (Spain).