if it was that small, it probably would have just burned in the atmosphere. if it had manages to pas the 2 asteroid belst, it could not be any bigger than like a truck, which would meaninglessly burn in the atmosphere.
i read somewhere that once every 10 years, an asteroid the size of a truck comes, and burnes up in the atmosphere. once every 100 years, a asteroid the size of the statue of libery comes, and mostly burnes up, sending small bits of rock down to earth. once every 1000 years, an asteroid the size of a mountain comes, burns up, and sends large rocks (like people-sized) into the earth. once every 10,000 years, an asteroid the size of 5-6 mountains comes, and sends even larger peices (like car or truck size) into earth. and finally, once every 1,000,000,000 years, an asteroid the size of the moon comes, and can scars the earth.
the only reason most of that hasn't happened is because large enough chinks go into the suns orbit. anything smaller will go in the asteropid bels. if a peice of rock comes from an asteroid belt, then it could be bad, but that almost never happens.
also, rememer that even when those things do come, only about .5% of the time do they actually hit the earth. they usually get caught in the suns orbit as they approach, fly pas the planets, and find the other side of the asteroid belt, or they collide with a planet (very rare)
so the chance of a large anough object hitting the earth that could actually do something is more like 1 in 200,000,000,000.