Task: Question Understanding
Input (English): Passage: However, on Tuesday, 7 February 2012, it was confirmed that Cardiff Blues would face Connacht Rugby at the Arms Park on Friday, 10 February 2012. The Pro14 League game result was a win for the Cardiff Blues 22–15 and attendance of 8,000. The following Tuesday, it was announced that the match against Ulster Rugby on Friday, 17 February, would also be at the Arms Park, resulting in a Blues win, 21–14 and attendance of 8,600. The agreement signed during 2009 tied Cardiff Blues to a 20-year contract to play a maximum of 18 games per season for a set fee, rather than per match at Cardiff City Stadium. But on 23 February, it was announced that the two Welsh derbies against the Scarlets and the Ospreys (rugby union) would be played at Cardiff City Stadium, rather than the Arms Park, because of Cardiff Blues anticipation that the attendance figures would far exceed the maximum capacity of 9,000. On 8 May 2012, it was announced that Cardiff Blues would be returning to the Arms Park on a permanent basis after just three years at the Cardiff City Stadium.
Question: How many years of the 20 year contract did the Cardiff Blues not play at Cardiff City Stadium?
Output (English): number