The difference from 50 years ago is staggering. In 1970, Canada made up 96.1% of players in the NHL, and by 1980 that number dropped to 81.9%. And it's changed ever so much each decade since:
USA: 11 (Coyle, Foligno, Frederic, Smith, Carlo, Clifton, Forbort, Grzelcyl, McAvoy, Reilly, Swayman)
Canada: 6 (Bergeron, DeBrusk, Greer, Hall, Marchand, Studnicka)
Czechia: 6 (Krejci, Lauko, Nosek, Pastrnak, Zacha, Zboril
Sweden: 3 (Lindholm, Stralman, Ullmark)