Norman Hubbard is Soccernet's resident anorak. If you have any questions on football facts, statistics or trivia, please send them to asknorman@hotmail.com and he'll try to answer as many as possible.

I've lately had the impression that a lot of red cards get issued in Champions League semi-finals (Thiago Motta's being the latest). It is understandable, since semi-finals are highly emotional affairs. Is this an accurate impression, or am I too swayed by the numerous images of Chelsea players being sent off when things aren't going their way? asked Chris Kreft

You have a point in one respect, though not another. Chelsea's semi-finals tend to end unhappily, but, remarkably, none of their players have ever been dismissed at this stage of the Champions League (though two, Didier Drogba and Jose Bosingwa, were banned retrospectively for incidents after their exit to Barcelona in the 2009 semi-finals and Drogba was red-carded in the 2008 final.) In fact, two opponents - Barcelona's Eric Abidal in 2009 and Monaco's Akis Zikos in 2004 - have been expelled against Chelsea at that stage.

Where you are definitely correct is that there has been a recent flurry of red cards in the semi-finals. Besides Motta's for Inter Milan against Barcelona, there were three in the Bayern Munich-Lyon tie: Bayern's Franck Ribery and Lyon's Jeremy Toulalan in Germany and Lyon's Cris in the second leg in France. In addition, there were two last season: Abidal and Manchester United's Darren Fletcher, rather unluckily expelled against Arsenal.

However, the picture changes there: Abidal and Fletcher were the first players to be sent off in the semi-finals since 2004. In the last decade, 40 semi-final matches have brought ten red cards. The others were Leeds' Alan Smith against Valencia in 2001, Monaco's Zikos against Chelsea in 2004 and the Deportivo la Coruna pair of Jorge Andrade and Nourredine Naybet in either leg against Porto in the same year.

But this season, it is definitely true to say that referees are reaching for red rather quicker in the last-four games. In this season's Champions League, there had been 23 dismissals in 120 matches (one every 5.2 games on average) before the four in four semi-final meetings.

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Which country has the lowest ranking of any to qualify for a World Cup? Is it North Korea for South Africa 2010, they are ranked at 102? asked Wan Hirman aka Xeqtr from Malaysia

It is North Korea, whose ranking has gone down to 106 since Wan sent in the question. Indeed the next lowest ranked team in this year's tournament is South Africa in 90th. However, FIFA only introduced their rankings in 1992, meaning that it is hard to compare the North Koreans and the South Africans with some of the outsiders from previous World Cups. But, from the 1994 World Cup, no side has arrived as much of an underdog (according to the rankings, anyway) as North Korea.

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How is it determined how many Champions League spots are available to a certain league? For example, the top leagues in England, Spain, and Italy are all given three automatic qualifying spots for the top three teams, and an additional Champions League play-off spot to the fourth place team. Is this determined by how well these leagues do in the Champions League, or some other factor? asked Mark Morsfield from Ann Arbor, Michigan, USA

It comes down to the UEFA coefficient system, which basically assesses the performance of teams from each country in European competition over the previous five seasons. Based on the number of wins and the progress of the teams, a score is produced for each season and then they are added up. It may be no surprise, therefore, that in 2007-08, England, with 17.875 from a year when Manchester United won the Champions League, Chelsea were runners-up and Liverpool a third semi-finalist, had the highest score.

Indeed, England, with 15.00, also had the highest ranking last season; although Barcelona won the Champions League, the Premier League provided three semi-finalists. It is worth noting that the UEFA Cup/Europa League also provides rankings points, so Scotland's highest rating (10.25) in the last five years came in 2008 when Rangers reached the UEFA Cup final. One subplot from this weekend's Champions League final is that Italy and Germany have very similar coefficients: should Inter win, Italy, currently just above Germany, will retain four places in the Champions League; if Bayern win, Germany will have four places - three automatically and one in the qualifying round - starting from the 2011-12 season.

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I'd like to know which forward in the Premier League has had the most misses in front of goal this season? asked Anthony Smuts.

To a certain extent, that depends upon your definition of a miss. What is factually correct is that the man with the most shots off target is also the division's top scorer. Didier Drogba scored 29 goals but did not trouble the goalkeeper with a further 71 efforts, the most in the division. Given his prolific return, however, it may seem unfair to brand him as the most profligate player. So an alternative answer could be Aston Villa captain Stiliyan Petrov, who had most shots (34) without scoring a single goal, or Wigan midfielder Jordi Gomez, who had most attempts (40) per goal scored (one).

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If you have a question for Norman, then you can email asknorman@hotmail.com