In 2015 a Thor’s Hammer was found with a metal detector on Flekstad farm in Steinkjer, Norway. This Thor’s Hammer dates from about 800-950 AD. This is only the 14th Thor’s Hammer ever found in Norway. In comparison, there are about 3,500 Viking swords which puts the hammer finds into perspective.
Thor’s hammers became more common when the Vikings were exposed to Christianity. The hammers became a statement that the wearer was a follower of the old faith, where Christians wore crosses.
Christianity came to Norway fairly late, about 1000AD. This might be the reason for the lack of Thor's Hammer finds in Norway. There was as much early interaction between Christians and followers of Thor!