There's a couple of things to consider here. First, the at-fault accident you had in January 2014 is over 3 years ago, so it shouldn't be impacting your premium anymore. Although you may still see it listed on your insurance record. Next, the average 6 month premium in Minnesota in 2017 was $629.
So your premium is actually lower than the state average. While you might be getting the best rate possible for you, it doesn't affect your premium to shop around. If you're curious about what would could be getting elsewhere, see our comparison app here.