Figured we can start up with another decade here. I've tried limiting myself to the 5-star films, although a future runner's-up list might be included later.

1970
Husbands (US - John Cassavetes)
Patton (US - Franklin Schaffner)
Gimme Shelter (US - Albert Maysles, David Maysles, Charlotte Mitchell Zwerin)
Catch-22 (US - Mike Nichols)
Hospital (US - Frederick Wiseman)
The Conformist (France/Italy/West Germany - Bernardo Bertolucci)
Little Big Man (US - Arthur Penn)
Woodstock (US - Michael Wadleigh)
Joe (US - John G. Avildsen) 

1971
Szerelem aka Love (Hungary - Kroly Makk)
A Clockwork Orange (UK - Stanley Kubrick)
Harold and Maude (US - Hal Ashby)
The Sorrow and the Pity (West Germany/France/Switzerland - Marcel Ophuls)
Macbeth (UK - Roman Polanski)
Punishment Park (US - Peter Watkins)
Johnny Got His Gun (US - Dalton Trumbo)

1972
Solaris (USSR - Andrei Tarkovsky)
Whats Up Doc? (US - Peter Bogdanovich)
The Godfather (US - Francis Ford Coppola)
The Bitter Tears of Petra Von Kant (West Germany - Rainer Werner Fassbinder)
Conquest of the Planet of the Apes (US - J. Lee Thompson)
Last Tango in Paris (Italy/France - Bernardo Bertolucci)
Aguirre the Wrath of God (West Germany/Peru - Werner Herzog)
The Getaway (US - Sam Peckinpah)
The Winter Soldier (US - Winterfilm Collective)

1973
Enter the Dragon (US - Robert Clouse)
The Exorcist (US - William Friedkin)
The Long Goodbye (US - Robert Altman)
Mean Streets (US - Martin Scorsese)
Paper Moon (US - Peter Bogdanovich)
O Lucky Man! (UK - Lindsay Anderson)
Juvenile Court (US - Frederick Wiseman)
Scenes From a Marriage (Sweden - Ingmar Bergman)
The Mother and the Whore (France - Jean Eustache)

1974
Monty Python and the Holy Grail (UK - Terry Gilliam/Terry Jones)
The Godfather Part II (US - Francis Ford Coppola) 
Chinatown (US - Roman Polanski)
Hearts and Minds (US - Peter Davies)
Young Frankenstein (US - Mel Brooks)
Blazing Saddles (US - Mel Brooks)
The Phantom of Liberty (France/Italy - Luis Bunuel)
A Woman Under the Influence (US - John Cassavettes)
The Mirror (USSR - Andrei Tarkovsky)
Distant Thunder (India - Satyajit Ray)
Celine and Julie Go Boating (France - Jacques Rivette)

1975
Nashville (US - Robert Altman)
Falsche Bewegung akaFalse Movement (West Germany - Wim Wenders)
Shivers (Canada - David Cronenberg)
Xala (Senegal - Ousmane Sembene)
The Passenger (Italy/Spain - Michelangelo Antonioni)
The Middleman (India - Satyajit Ray)
Numro Deux (France - Jean-Luc Godard/Anne-Marie Miville)
The Travelling Players (Greece - Theo Angelopoulos)

1976
All the Presidents Men (US - Alan J. Pakula)
Harlan County USA (US - Barbara Kopple)
Taxi Driver (US - Martin Scorsese)
In the Realm of the Senses (France/Japan - Nagisa Oshima)
Network (US - Sydney Lumet)
The Last Supper (Cuba - Toms Gutirrez Alea)
The Man Who Fell to Earth (UK - Nicholas Roeg)
Rocky (US - John G. Avilsden)
Family Plot (US - Alfred Hitchcock)
Meat (US - Frederick Wiseman)

1977
Star Wars (US - George Lucas)
Annie Hall (US - Woody Allen)
Eraserhead (US - David Lynch)
Saturday Night Fever (US - John Badham)
Roots (US - Marvin J. Chomsky, David Greene, Gilbert Moses, John Erman)
Hitler, a Film From Germany (West Germany/France/UK - Hans-Jrgen Syberberg)

1978
Dawn of the Dead (US - George A. Romero)
Pennies From Heaven (UK - Piers Haggard)
Interiors (US - Woody Allen)
The Deer Hunter (US - Michael Cimeno)
Perceval (France - Eric Rohmer)

1979
Apocalypse Now (US - Francis Ford Coppola)
Monty Pythons Life of Brian (UK - Terry Jones)
All That Jazz (US - Bob Fosse)
Quadrophenia (UK - Franc Roddam)
Real Life (US - Albert Brooks)

There are definitely a few "bubbling under" contenders, notably Autumn Sonata, Halloween, Manhattan, Nosferatu, Alien, The Marriage of Maria Braun, Providence, Carrie, Dog Day Afternoon, Cabaret, and it goes on like this.

Although 1979 might seem underrepresented, two of those films would probably be in my top 20, and Quadrophenia somewhere in my top 50.

* Edit for Husbands