"Your odds of dying in a terrorist attack...

... are still far, far lower than dying from just about anything else." See point #8 at that link, which points out:

In the last five years, the odds of an American being killed in a terrorist attack have been about 1 in 20 million (that’s including both domestic attacks and overseas attacks).

And Megan McArdle explains why deadly terrorist attacks are "so rare":

I can right now think of several terrorist strategies which would kill a lot of people and be nearly impossible to defend against. I'm not going to offer terrorists any ideas, but here's one that's already been tried: the DC sniper. They were caught only because they were too poor to switch the cars they were shooting from; a slightly better bankrolled effort could have effectively gone on forever. And you can't really imagine how you'd re-engineer America to defend against such attacks.

So why don't they happen more? The most convincing answer I've gotten to that question is that fostering terror is only one of the aims of a terrorist attack. These attacks also function as recruiting, and as fundraising promotions for your terrorist organization. There are what you might [call] business considerations, in other words, and those business considerations dictate the kinds of attacks that terrorists want to carry out.

Thank God, randomly shooting one person every week or so does not satisfy the business plan. Terrorists want large, splashy attacks on specific sorts of targets that have high emotional resonance for both the victims and the people on your side who you hope to recruit, or tap for money. This helps explain why Al Qaeda was so obsessed with the Twin Towers, a place that--until they fell--most New Yorkers regarded as a rather ugly landmark containing some so-so office space. To a terrorist group looking for publicity, on the other hand, it had immense symbolic value: the tallest building in America's biggest city, with the hubristic name of "World Trade Center".

That's why we don't get high-frequency, low-intensity attacks on crowded spaces near some Texas town that no one in Abottabad has ever heard of. When attacks on those places happen, they tend to be the provenance of local lunatics for whom the nearby mall, or primary school, has some immense symbolic emotional importance.

And thankfully, there are not nearly as many lunatics as there are schools, or malls, or even marathons. That's why most of our public spaces are safe from mad bombers--and I'm glad to say, why they will remain so.