No plane has crashed due to turbulence. There is nothing to worry about. If you want to look at it in the year 2000 there were 49,000 airplane flights in one day and they fly everyday. And if you go on an airline with good maintenence i.e european,american,middleeastern,american,australasian,asian and a few others then you will be fine. Just don't fly Helios, even before that crash the mecahnic of that airline said he would not let that aircraft fly as it had a problem on a flight before ending in an emergency landing but the airline threatened to sack him if he didnt sign the aircraft back into service.
You can easily look up on google which airlines are bad. but like i said that is the only one in europe that i can think of