Norway first participated at the Olympic Games in 1900, and has sent athletes to compete in every Games since then, except for the sparsely attended 1904 Games and the 1980 Summer Olympics in Moscow when they participated in the American-led boycott. Norway leads the overall medal tables at the Winter Olympic Games by a considerable margin. Famous Norwegian winter sport athletes includes biathlete Ole Einar Bjørndalen, speed skaters Johan Olav Koss and Hjalmar Andersen, figure skater Sonja Henie and cross-country skiers Marit Bjørgen and Bjørn Dæhlie.