i have a question about the recent gfc we had .
Assuiming we have a recovery from the GFC why might we still have 4.5% unemplyment?

is this because we may now have frictional unemployment as people are looking for a job, cyclical unemployment would reduce however structural unemplyment would still be realtively high? and would it have anything to do with the participation rate and the portion of people who choose not to work either way?
thx in advance