High fluctuation is not always the case. Right now it seems that we have again a short span of a "golden age" in aviation, means a lot of airlines are searching right now(apart from the usual China/ME which is not for everyone).
Of course pilots try to get themself into a good position for the next dry years to come. That's all. 10% is not a standard value constantly going over the last few years(and the next few) I am pretty sure.