Thomas Rhett

Thomas Rhett

John Shearer

Plus, The National debuts at No. 4.

Thomas Rhett leaps from No. 25 to No. 1 on the Billboard Artist 100 chart (dated Sept. 30) to become the top musical act in the U.S. He's only the second country act to rule the ranking this year, following Chris Stapleton on the May 27-dated chart.

The Artist 100, which launched in July 2014, measures artist activity across key metrics of music consumption, blending album and track sales, radio airplay, streaming and social media fan interaction to provide a weekly multi-dimensional ranking of artist popularity.

Rhett's jump is powered by his third studio album, Life Changes, which arrives as his first No. 1 on the Billboard 200 with 123,000 equivalent album units in the week ending Sept. 14, according to Nielsen Music. He's the first country act to lead the Billboard 200 this year; Stapleton arrived at No. 2 on the Billboard 200 dated May 27, the week that he topped the Artist 100.

Album sales contribute the majority of Rhett's Artist 100 points (74 percent), followed by digital song sales (11 percent). Concurrently, the album's latest single, "Unforgettable," hits the Hot Country Songs chart's top five.

Country stars have rarely hit No. 1 since the Artist 100 began, as only seven have led to date (for nine total weeks) since the chart's inception:

Country Acts Atop the Billboard Artist 100
Artist, Chart Date(s) at No. 1
Thomas Rhett, Sept. 3, 2017
Chris Stapleton, May 27, 2017
Luke Bryan, Aug. 29, 2015
Zac Brown Band, May 16, 2015
Florida Georgia Line, Nov. 1, 2014 & Sept. 17, 2016
Jason Aldean, Oct. 25, 2014 & Oct. 1, 2016
Blake Shelton, Oct. 18, 2014

Meanwhile, The National debuts at No. 4 on the Artist 100, as the rock group's seventh studio album, Sleep Well Beast, opens at No. 2 on the Billboard 200 (64,000 units).

Also in the Artist 100's top five, Taylor Swift dips to No. 2 after a record 33 weeks at No. 1, Imagine Dragons hold at No. 3 and Ed Sheeran keeps at No. 5.

Check out this week's full Artist 100 here.