A thread of nostalgia weaves together the year’s biggest artist, album and song: Taylor Swift, her late-‘80s-pop retrofit 1989 and the soul throwback “Uptown Funk!” by Mark Ronson featuring Bruno Mars.

The Year in Music 2015: See All the Billboard Charts

Swift rules as Billboard’s top artist of 2015, thanks largely to the runaway success of 1989 (named for her birth year), the record’s smash singles and the squad leader’s sold-out stadium tour. It also marks the second time Swift, who turns 26 on Dec. 13, is the year’s top artist, making her only the second woman to claim that crown twice, following Adele in 2011 and 2012. Swift last ruled in 2009, after her second record Fearless spent 11 nonconsecutive weeks atop the Billboard 200.

But back then, the singer-songwriter was still firmly a country act. Fast-forward to 2014, when Swift easily, and deliberately, made the transition from Nashville darling to full-on pop star, dropping the relentlessly upbeat “Shake It Off” (which debuted directly at No. 1 on the Billboard Hot 100) as 1989’s lead single. Haters were gonna hate on Swift, but few could ultimately resist her fifth album’s synthy pop incandescence: 1989 debuted at No. 1 on the Billboard 200 with 1.29 million copies sold in its first week, according to Nielsen Music, marking her third straight album to bow with one million sold (and making Swift the first act to notch three million-selling weeks). The Big Machine release then spent 11 nonconsecutive frames leading the Billboard 200 and lingered in the top 10 for its first 53 weeks — becoming only the fifth album to spend its first year in the chart’s top 10.

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Given all those feats, it’s perhaps no surprise that 1989 is the Billboard 200’s biggest album of the year -- the second time Swift’s earned the distinction (Fearless also reigned this chart in 2009). She’s only the fourth act to earn top year-end honors with two albums, joining the ranks of 50 Cent (Get Rich or Die Tryin’ in 2003 and The Massacre in 2005), Whitney Houston (her self-titled debut in 1986 and The Bodyguard soundtrack in 1993) and Elton John (Goodbye Yellow Brick Road in 1974 and Greatest Hits in 1975). Swift also dominated the singles universe in 2015, finishing as the No. 2 Hot 100 Artist -- behind only The Weeknd -- and claiming five entries on the year-end Hot 100 (Nos. 7, 15, 18, 29 and 57).

But the champion of this year’s Hot 100 roundup is Mark Ronson, whose retro workout juggernaut “Uptown Funk!,” featuring Bruno Mars (RCA), trumped all else. Channeling the likes of vintage Prince and The Gap Band, the “ice cold” track zoomed to No. 1 on the weekly Hot 100 chart dated Jan. 17 and spent a near-record 14 weeks there -- landing the single in a seven-way tie for the second-longest run at No. 1, behind only the 16-week reign of Mariah Carey and Boyz II Men’s “One Sweet Day.” Still, “Funk!” made chart history, securing the most weeks at No. 1 in the 2010s and the longest No. 1-run since The Black Eyed Peas’ “I Gotta Feeling” scored 14 weeks at No. 1 in 2009.

Notably, “Funk!” is the first year-end Hot 100 No. 1 that’s lead artist doesn’t actually sing the song. Ronson co-produced and co-wrote the tune, and also played guitar, but Mars voices the smash. “Funk!” also gives Mars his first year-end chart topper, after scoring a pair of top 10s -- one in 2013 (“When I Was Your Man,” No. 8) and one in 2011 (“Grenade,” No. 6). Following “Funk!” on the Hot 100 recap, respectively, are Ed Sheeran’s “Thinking Out Loud”; Wiz Khalifa’s “See You Again” featuring Charlie Puth and Fetty Wap’s “Trap Queen.”

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Fetty Wap is also 2015’s biggest discovery: The New Jersey rapper leads the top new artists recap, courtesy of a whopping seven Hot 100 hits during the chart year -- including the top 10s “Trap Queen” (which spent three weeks at No. 2), “679” (No. 4) and “My Way” (No. 7) -- and his self-titled debut, which opened at No. 1 on Billboard 200. Following close behind on the new artist list are Columbia’s singer/songwriter Hozier and MCA Nashville’s college football player-turned-country star Sam Hunt, who both enjoyed top three-charting albums on the Billboard 200.

Billboard’s year-end music recaps are based on chart performance between the Dec. 6, 2014 and Nov. 28, 2015 charts. The year-end top artist category ranks the best-performing acts of the year derived from activity on the Billboard 200 albums tally and the Billboard Hot 100 singles list, as well as streaming, social and boxscore data. Data registered before or after a title's chart run are not considered in these standings. That methodology detail, and the December-November time period, account for some of the differences between these lists and the calendar-year recaps that are compiled independently by Nielsen Music.