A quote from Max Mayfield:

"I don't remember this happening before in such a short period of time," National Hurricane Center director Max Mayfield told reporters, "and the season is only half-over."
It might be a generation before hurricane weather slips back into a quiet phase, he and other experts say.
"The hurricane threat is much greater than it was in the 1970s through early 1990s," said federal meteorologist Stan Goldenberg, who flew around Hurricane Ivan in research aircraft as it approached Mobile, Ala. "It could last another 10 to 40 years."

Can anyone please explain this one?

Here is the article:
http://www.sun-sentinel.com/news/local/southflorida/sfl-917hurricanecycle,0,4485692.story?coll=sfla-news-sfla