What is the origin of lussekatter?

Lussekatter, or St. Lucia buns, originated in Sweden and are traditionally eaten on St. Lucia's Day on December 13th. They are saffron-flavored buns usually shaped like an "S" or a double "S" and are often garnished with raisins or currants. The buns are a significant part of the celebration of St. Lucia's Day in Scandinavian countries.