Why Are So Many Hurricanes Hitting USA?

Another Hurricane Wilma is set to hit Florida within a week.

This accounts for the 21st tropical storm in the Altantic within 2005 alone. Tying it with a record high in 1933.

Why are the hurricanes hitting this area so frequently? Hurricanes are caused partly by warmer ocean surface that does not dissipate (see animation on formation of hurricane). The USA is rated the country with the highest amount of greenhouse-gas emissions in the world (China coming in fast in second place). Green house effects prevents heat on land and sea from dissipating into space by reflecting these heat back from the atmosphere. Hence increasing average temperature on land and sea.

Is this increased rate of hurricanes a concidence? Or is this a sign of the damages that are been done?