Congressional approval ratings rise

Even though Congress has not enjoyed high public approval ratings for a long time, the numbers keep moving up. It seems odd to me given the intense scrutiny the media and the Republicans have put on the Democrat's agenda. Since the economy has not really improved and the public's confidence that it will in the future remains low, how can the approval ratings be going up? I know that people always like their own Congressmen, but for the national whole to rise during a time where not much has been done except debate, maybe the public is shifting more blue.