Just checked the stats.
Of the last 5 years semi finalists, 8 were from Spain, 5 from England and 5 from Germany. 18 out of 20. So those Countries Associations get 4 places.
Of England's 5 semi Finalists, Chelsea supplied 2 and Manchester United supplied 2. Without Chelsea and Man Utds places, England would have had just 1 semi finalist, so we would get only 3 places. Which would have meant arsenal's 4th place this year and 2010 they would not have qualified.
So Chelsea and Man Utd have got you into the Champions League 2 times in the last 3 years.