Depends how good your driving record is and the insurance company. With State farm it made about 150 difference on my yearly rate. For me it was 1/5th of my rate.
We all have clean records so that is a non-issue. Miles racked up due to all of us looking for jobs. And yes, the mileage could change the following year.
My sister who lives in UT said they also receive these but her agent takes care of it so they have cheaper premiums. They drive a lot due to his job.