How has it been having “Shake It Off” stuck in your head this past week and a half? If it makes you feel any better, you are not alone. After its first full week out, the song jumped from No. 69 on the Billboard Hot 100 to No. 1, on the back of strong sales, radio airplay, streaming, and basically everything else. This is Taylor Swift’s second No. 1, after “We Are Never Ever Getting Back Together.” Coming in at No. 2 is Nicki Minaj’s “Anaconda,” which was helped by its record-breaking video. MAGIC!’s “Rude” dropped to No. 5 because of Nicki and Taylor, and because reggae is exclusively for summer breaks.