According to some semi-official sources I found with a quick Googling, Sweden was mostly self-sufficient up until the mid-90's. Dunno how many people lived there during the 90's, but I take it that it was more than a million?

Of course, things will change once harvests will start failing, and if you guys had just a bad of a harvest as we had this year (Finland), then it doesn't matter if 50% or 10% of the food comes from local sources; you're going to be reliant on imports anyway.