Small list in terms of amount of #1 songs.
Like 1980, no Canadian artists were featured at the top of the charts.
Older Polls:
1964-http://boards.straightdope.com/sdmb/showthread.php?t=767524
1965-http://boards.straightdope.com/sdmb/showthread.php?t=767714
1966-http://boards.straightdope.com/sdmb/showthread.php?t=767890
1967-http://boards.straightdope.com/sdmb/showthread.php?t=768306
1968-http://boards.straightdope.com/sdmb/showthread.php?t=768597
1969-http://boards.straightdope.com/sdmb/showthread.php?t=768867
1970-http://boards.straightdope.com/sdmb/showthread.php?t=769085
1971-http://boards.straightdope.com/sdmb/showthread.php?t=769397
1972-http://boards.straightdope.com/sdmb/showthread.php?t=769624
1973-http://boards.straightdope.com/sdmb/showthread.php?t=769837
1974-http://boards.straightdope.com/sdmb/showthread.php?t=770060
1975-http://boards.straightdope.com/sdmb/showthread.php?t=770295
1976-http://boards.straightdope.com/sdmb/showthread.php?t=770513
1977-http://boards.straightdope.com/sdmb/showthread.php?t=770753
1978-http://boards.straightdope.com/sdmb/showthread.php?t=771010
1979-http://boards.straightdope.com/sdmb/showthread.php?t=771209
1980-http://boards.straightdope.com/sdmb/showthread.php?t=771416
You may vote for more than one song.