Eminem, 2014.

Eminem performs during Midtown Music Festival in Atlanta, Georgia on September 20, 2014.

Perry Julien

It was a landmark move when it was announced and remains one of the key steps in the evolution of the Billboard Hot 100: 10 years ago today, on the chart dated Feb. 12, 2005, digital download sales began contributing to the survey.

"We have eagerly anticipated the moment when we could begin to integrate digital sales into the Hot 100," wrote then-Billboard director of charts Geoff Mayfield in that week's print issue. "It has been a priority for labels, and even some music fans, that we derive more utility from digital sales data."

The Billboard Hot 100: Week of Feb. 12, 2005

"We are absolutely thrilled that the advent of digital downloads brings a viable sales component back to the Hot 100," added Silvio Pietroluongo, who still oversees the survey (and has since added responsibilites as VP of charts and data development for Billboard and sister publication The Hollywood Reporter).

"Radio stations are programmed to reflect the wants of their listeners, but there is no substitute to measure a song's true popularity than the purchase by a consumer," Pietroluongo wrote. "The combination of accurate airplay data with a strong sales base further secures the Hot 100's place as the definitive U.S. singles chart."

The addition of paid downloads, which Nielsen Music had begun tracking in 2003, leading Billboard to start the Digital Songs chart that year, restored balance to the Hot 100, which had become heavily airplay-driven as sales of CD and cassette singles had strongly regressed by 2005. The makeover became another milestone in the history of the chart, which began on Aug. 4, 1958 as a scorecard of radio airplay and sales (of 45 RPM vinyl singles). (Earlier pop charts had also tracked jukebox popularity.)

Other noteworthy changes to the Hot 100 would keep coming, including the adoption of Nielsen-based airplay and sales numbers in 1991, replacing the decades-old methodology of lists submitted by stations and retailers. More recently, AOL and Yahoo! radio streaming was added in 2007, with an expanded array of services, including on-demand streaming, joining the mix in 2012. Video streaming, via YouTube, entered into the chart's formula as of 2013.

As consumers began or continued to digitize their music libraries 10 years ago (on home computers plugged into walls, not yet on phones), certain songs notably benefited from the addition of download data to the Hot 100. While Mario's "Let Me Love You" remained at No. 1 (for a seventh of nine total weeks on top), Kelly Clarkson's "Since U Been Gone" jumped 16-9; Gwen Stefani's "Rich Girl," featuring Eve, surged 25-17; and Eminem's "Like Toy Soldiers" vaulted 60-34.

Rihanna, Kanye West, Paul McCartney & Ellie Goulding Hit Hot 100's Top 10; Mark Ronson, Bruno Mars Still No. 1

Of course, download sales were still in the early stages of their rise in 2005. Green Day's "Boulevard of Broken Dreams" topped the Feb. 12 Digital Songs chart with 36,000 downloads sold (and only the next five songs below sold more than 20,000 apiece). Ten years later, Mark Ronson's "Uptown Funk!," featuring Bruno Mars, reigns with 319,000 sold, while 36,000 in sales would place a song at No. 36 on Digital Songs this week. (And, while, 10 years ago, just six songs passed 20,000 in weekly sales, 82 did this week.)

"The addition of digital downloads to the Hot 100," Pietroluongo summarized 10 years ago, "allows us to once again provide a voice to a constituency that Billboard has always valued: the music consumer."