SLK North America Map Update Questions

Hello,

My wife has a 2014 SLK with the NAV build in. Great car. But the maps seem old and need an update as the local road construction is not up-to-date.

I see MB has released 2015 map updates for Europe, but I don't see any for North America yet. And the "Here.com" web site indicates that updates have to be done by a MB dealer and cannot be done by the customer?

I would assume map updates come out every year but apparently not. Can folks here in the US please tell me how the US map updates work, when they might come out for 2016, and if they can be customer installed?

Thanks in advance.