Less terrorism or better government intervention?

17 Apr 2013 • nytimes.com

The bombing of the Boston Marathon on Monday was the end of more than a decade in which the United States experienced strikingly few terrorist attacks, in part because of the far more aggressive law enforcement tactics that arose after the Sept. 11, 2001, attacks.

In fact, the Sept. 11 attacks were an anomaly in an overall gradual decline in the number of terrorist attacks since the 1970s, according to the Global Terrorism Database, one of the most authoritative sources of terrorism statistics, which is maintained by a consortium of researchers and based at the University of Maryland.

[emphasis mine]

Which is it?  Is it because of more aggressive law enforcement tactics or simply the continuation of the overall trend since the 1970s?  Are we mostly safe to begin with and the increased surveillance, reduced liberties, and increasing "show me your papers" government mentality all a complete waste?  ...or do we live in a world more dangerous than we know where terrorist attacks are a common event skillfully (or luckily) thwarted each day by aggressive law enforcement?

I'm not sure I really even want to know.