Hi Alex,

Good question! This depends a lot on the flare intensity and the phase of the solar cycle. As well as on how strong the solar cycle is . For example from http://solarmonitor.org/ you can look how many flares have happened a certain (bottom of the page). C-class are weakest, M-class moderate flares and X-class the strongest flares (classification according to their X-ray output).

During solar minimum strong and moderate flares occur very rarely, but very weak flares you can still see regularly. For example, during the recent minimum there were several years without strong flares. At solar maximum flares occur several times per day and strong ones often as well. During the on-going solar 24 there have been 15 X-ray flares so far (all in 2011 and 2012).

Flares also occur quite irregularly. Sometimes there are long periods without much activity and then some strong active region appear and produce manyf big flares in a few days.

Emilia