I’ll fill in:
Not the “record company” (though I’ve heard that story too) but his songwriting partner Jim Vallance. Apologies for continuing the hijack on a song that doesn’t even qualify for this thread.
I’m surprised by the number of titles that come up if you search at Allmusic. 69 tracks with ‘1975’ as the title.
3030 by Deltron 3030.
1997 - Sleepytime Gorilla Museum
Most of the ones I can fill in from my music collection at work are repeats:
1976 - Alan Jackson
1990 - Michael W. Smith
1999 - The Wilkinsons. (Which, as a bit of trivia, I remember was originally composed as ‘1989’, and took so long to get recorded that they had to update the decade.)
I’ve got “73” by Jennifer Hanson, which is definitely a reference to 1973 in context. Also the 1812 Overture. 
“Nineteen Forty-Eightish”, Roy Harper
1014 A.D. - Cruachan (hope that title’s technically allowed)
1930 - Merzbow (If you consider that a song :), no idea if it’s a year and I don’t know if we’ll ever find out)
1945 - Social Distortion
1989 - Mindless Self Indulgence
1999 - Residents (pseudo-cover of Prince’s song)
1984 - Spirit.
A.D. 1928, A.D. 1958 - Styx
2084 - Ayreon
1974 - Robyn Hitchcock
Does this count?
In The Year 2525 - Zager And Evans
That song was already mentioned upthread, but you are right - it is called “In the Year 2525” not “2525,” and thus excluded by the OP.
However, Laibach’s cover of the song is simply called “2525” so it counts!
1905 - Shona Laing.
I don’t know about the Internet, but people posting links like this sure do. 
1941 - Nilsson
All by Robert Fripp:
1983
1984
1985
1986
1987
1988
1989
Nineteen63 (1963) by New Order
2095 by ELO
But that might be hard to list around 
The Submarines - 1940
Discover America - 1986
Adding to the list:
La bottine souriante - 2033