Hi.
Solar flares don't actually hit the earth. They occur in the lower part of the Sun's corona. We only see X-rays and other kinds of light that they emit. That is pretty common, although how often they happens goes up and down every eleven years in what is called the solar activity cycle.

You are probably really asking about coronal mass ejection (CME), large clouds of material that blast of the Sun. This happens pretty regularly (about once every other day at solar minimum, a few a day at solar maximum). Most of these do not hit Earth (they go off in other directions), but some do. I don't remember exactly how many. When they do hit we sometimes get to see the aurora (the northern or southern lights) in the sky at night.

More about CMEs here:

http://www.windows.ucar.e...ty/solar_storms.html

http://www-istp.gsfc.nasa.../cmeposter/html.html

Terry