Increase in asteroid strikes?

http://www.nytimes.com/2013/11/07/science/space/more-large-asteroid-strikes-are-likely-scientists-find.html?ref=science&_r=0
In February a Russian town was hit by a 60 foot asteroid and injured over 1000 people.  That asteroid was ONLY 60 feet.  Many asteroids are floating throughout our solar system.  We have been able to track many of these asteroids, especially those that are large enough to destroy the Earth as we know it.  We have estimated to have found 95% of these asteroids, over 1 kilometer wide, and none of them seem to be on a path to hit Earth any time soon.  However, if we look at smaller asteroids, we have  only found 0.5% of them.  They are not as easily found and can pose a problem.  Perhaps if a few of these smaller asteroids hit Earth rather than a single large one, the whole Earth would be destroyed.  These asteroids that can move at tens of thousands of miles per hour could devastate Earth if multiple smaller asteroids hit at once.  Scientists originally thought occurrences such as this would only happen maybe once a century, however now they are being pushed to believe that asteroid impacts might occur once every few decades.