January 1 – January 7, 2012: Sexy and I Know It – LMFAO
January 8 – February 4, 2012: We Found Love – Rihanna featuring Calvin Harris
February 5 – February 18, 2012: Set Fire to the Rain – Adele
February 19 – March 3, 2012: Stronger (What Doesn’t Kill You) – Kelly Clarkson
March 4 – March 10, 2012: Part of Me – Katy Perry
March 11 – April 7, 2012: We Are Young – Fun featuring Janelle Monáe
April 8 – April 14, 2012: Somebody That I Used to Know – Gotye featuring Kimbra
April 15 – May 5, 2012: Call Me Maybe – Carly Rae Jepsen
May 6 – May 12, 2012: Somebody That I Used to Know – Gotye featuring Kimbra
May 13 – June 2, 2012: Call Me Maybe – Carly Rae Jepsen
June 3 – June 9, 2012: Somebody That I Used to Know – Gotye featuring Kimbra
June 10 – August 25, 2012: Call Me Maybe – Carly Rae Jepsen
August 26 – September 1, 2012: Whistle – Flo Rida
September 2 – September 8, 2012: We Are Never Ever Getting Back Together – Taylor Swift
September 9 – September 15, 2012: One More Night – Maroon 5
September 16 – October 6, 2012: Gangnam Style – Psy
October 7 – October 13, 2012: One More Night – Maroon 5
October 14 – November 3, 2012: Diamonds – Rihanna
November 4 – November 10, 2012: Locked Out of Heaven – Bruno Mars
November 11 – December 1, 2012: Diamonds – Rihanna
December 2 – December 8, 2012: Locked Out of Heaven – Bruno Mars
December 9 – December 15, 2012: Diamonds – Rihanna
December 16 – December 29, 2012: Locked Out of Heaven – Bruno Mars
December 30, 2012 – January 5, 2013: Locked Out of Heaven – Bruno Mars

(Data is compiled from various charts, including Billboard’s “Pop,” “Rock,” “Airplay,” “R&B/Dance,” and “Singles” Charts. The “Hot 100” is the primary chart used for this list.)