As Pharrell Williams continues his reign atop the Billboard Hot 100 for the 10th week, “Happy” joins the ranks of only 28 songs that have logged that much time at No. 1 in the chart’s 55 years.

The all-time record belongs to Mariah Carey and Boyz II Men’s “One Sweet Day,” which spent 16 weeks at No. 1 in 1996-1996, but Williams has an ace in his pocket: he was featured on the last song to top the chart for more than 10 weeks: Robin Thicke’s “Blurred Lines,” featuring Williams and T.I.

The big question is if “Happy” will finally be toppled next week by John Legend’s “All of Me,” which has been stuck at No. 2 for six weeks. Legend’s song continues to gain steam at radio and via streaming.

As they have before, Jason Derulo’s “Talk Dirty,” featuring 2 Chainz, and Katy Perry’s “Dark Horse,” featuring Juicy J, trade places, with “Horse” rising 4-3 and “Dirty” retreating 3-4.

DJ Snake scores his first top 5 hit as “Turn Down For What,” featuring Lil Jon, move 7-5, pushing Idina Menzel’s “Let It Go” 5-6.

Like DJ Snake, Iggy Azalea scores her first top 10 hit, as “Fancy,” featuring Charli XCX, soars 18-7. That’s not the only good news for the Australian rapper: her debut album, “The New Classic,” enters the Billboard 200 at No. 3.  Azalea is the first female rapper to have her debut single reach the top 10 since M.I.A. with “Paper Planes” in 2008, according to Billboard. Guest vocalist  Charli XCX matches her previous Billboard Hot 100 high from when she guested on Icona Pop’s “I Love It” last year.

Bastille’s first Top 10 hit, “Pompeii,” slides 6-8, while Justin Timberlake’s “Not A Bad Thing” and Chris Brown’s “Loyal,” featuring Lil Wayne and French Montana or Too $hort or Tyga (there are two versions floating around), each fall one spot to No. 9 and No. 10, respectively.