Based on thousands of votes this is what topten.com came up with for the top 10 songs of 2015. The list continues till top 500 so see where your faves ended up.
http://www.thetoptens.com/2015-songs/
1. See You Again - Wiz Khalifa (7% of the votes)
2. Hello - Adele (5% of the votes)
3. Love Me Like You Do - Ellie Goulding (5% of the votes)
4. Elastic Heart - Sia (4% of the votes)
5. Gold - Imagine Dragons (3% of the votes)
6. Locked Away - R. City (2% of the votes)
7. Sugar - Maroon 5 (2% of the votes)
8. Uma Thurman - Fall Out Boy (2% of the votes)
9. I Really Like You - Carly Rae Jepsen (2% of the votes) 
10. Defeated - Breaking Benjamin (2% of the votes)
Others:
#12 - 45S - Rihanna
#18 Wildest Dreams - Taylor Swift
#47 Carly Rae Jepsen - Run Away With Me
#169 I Bet - Ciara
#462 Til It Happens to You - Lady Gaga
