I was hoping to catch this sooner, but the forums here have just hit the 1,980 registered user. As such, here’s the top billboard single (in the US) for 1980, Blondie’s “Call Me”:
https://www.youtube.com/watch?v=y6QBaZHltJw
Yes, before you ask, I’ll update when I check back in a little bit. 
Do you have the stat of how many of those users are “regularly active”?
We’re around 750-950 active daily users (unique). This is approximated between Google analytics and our own hosted piwik. (This is likely about 30% low roughly based on probable ad-blocker use, which I encourage).
Speaking of which, you just reminded me to check and we’re up to 1,984 registered users, so here’s 1984’s top billboard track for the year (US), Prince’s “When Doves Cry”:
Ugh, I wanted to post one of the better songs from 1990, but here’s Wilson Phillips “Hold On”:
Hah, 2,000! I’m not a big Faith Hill fan (the #1 for 2000), but I’ll post #2 instead…
Also, you may not like these, but at this rate I’ll be out of dates in a few days!
I missed yesterday, so your punishment is 2009’s #1 Billboard top 100 song, Boom Boom Pow, by the Black Eyes Peas:
Ouch. 2009 was a dark year…
