What is true regarding exit ramps from motorways?
On the right is more common since it is safest (you naturally keep to the right on the road and avoid changing lanes when you intend to turn off). However: “Exit ramps from a motorway can sometimes be on the left.” (Du och jag i trafiken [You and me in traffic], 28th Edition, page 263).
Here is an example of an exit to the left: Google Maps, E4/E20 Solna
More examples of explanations: