That happens a lot when semi-popular teams begin winning. Or even when they don't; I remember when the Diego signing about doubled the membership here back in the day.:D
How much of a boss is Jose Mourinho? This much... Great article about going all the way for a dedicated supporter.
http://sportsillustrated.cnn.com/soccer/news/20130410/real-madrid-fan-jose-mourinho/#ixzz2Q9vYdOBK