Replying to the last 2 posts....did not know that about 1968. I got one question for Billboard. Are you guys having double standards? Why would you do that for Hey Jude but not for You Light Up My Life? And for those that do not know, while AT40 compiled their own top 100 of 1977 with I Just Want.... at #1, Billboard's top 100 of 1977 had Tonight's the Night at #1. If you do it once, you really need to do every time such a situation exists. BTW, how bizarre is that, Tonight's the Night did end up being #1 for the year whereas You Light Up My Life (#3 in 1978) did not in any year.
As to how those other charts were complied (by Fred Bronson not by me), yes it was the inverse system that you alluded to and it applied to the entire HOT 100. Plus 50 bonus points were awarded for every week that a song was #1.
Here now are all the #1 songs of the year for the rock era until Soundscan started since I am sure some of you are curious.
1956...Don't Be Cruel/Hound Dog
1957...Love Letters in the Sand
1958...It's All in the Game
1959...Mack the Knife
1960...Theme from "A Summer Place"
1961...Tossin and Turnin'
1962...The Twist (was #6 in 1960)
1963...Sugar Shack
1964...I Want to Hold your Hand
1965...Satisfaction
1966...I'm a Believer
1967...To Sir With Love
1968...Hey Jude
1969...Aquarius/Let the Sun Shine In
1970...Raindrops Keep Falling on my Head
1971...Maggie May/Reason to Believe
1972...American Pie (sorry bestmusicexpert)
1973...Tie a Yellow Ribbon Round the Ole Oak tree
1974...The Way We Were
1975...Rhinestone Cowboy
1976...Tonight's the Night
1977...You Light Up My Life
1978...Le Freak (#2 Shadow Dancing, 3 Stayin Alive, 4 Night Fever)
1979...Hot Stuff (#2 YMCA, the highest ever non #1 song)
1980...Another One Bites the Dust
1981...Physical (#2 Bette Davis Eyes, 3 Endless Love)
1982...Eye of the Tiger
1983...Every Breath You Take
1984...When Doves Cry
1985...Careless Whisper
1986...That's What Friends are For
1987...Faith
1988...Need You Tonight
1989...Another Day in Paradise
1990...Love Takes Time
1991...Everything I Do
Both the Beatles and Rod Stewart snared 2 #1 songs of the year