It's certainly true that not everything Ryanair have tried has worked in Scandinavia, but then route closures and base closures have also happened elsewhere in Europe. Overall, the growth still continues.
In 2012, Ryanair were forecasting 2.2 million passengers for Rygge for that year. The 2015 forecast is down to 1.35 million. Similarly Skavsta has a forecast of 1.1 million for next year, compared to over 2 million a few years ago, so those are pretty big cuts.
But Anna isn't that in keeping with many airports where there is initially high demand but then it falls to its own level.
In addition the shortage of aircraft during peak summer season meant that marginal routes got culled first rather than high frequency high yielding routes.