All 20 of these songs were released in the last 40 months, which makes sense. This is the period in which digital song sales have exploded. The oldest song on the list is "Apologize" by Timbaland featuring OneRepublic, which was released in April 2007. The newest is "TiK ToK," which was released in October 2009.
Surprisingly, four of the top 20 digital sellers failed to reach #1 on the weekly Digital Songs sales chart. That simply means there was never a week when the hit was the best-selling download in the country. These songs are Jason Mraz's "I'm Yours," Taylor Swift's "Love Story," Katy Perry's "Hot N Cold" and "Need You Now."
Seven of the top 20 digital sellers failed to reach #1 on Billboard's Hot 100, which combines digital sales and radio airplay points. These smashes are the four songs listed above plus Train's "Hey, Soul Sister," Lady Gaga's "Bad Romance" and Miley Cyrus' "Party In The U.S.A."
Here are the top 20 songs in digital history, as measured by Nielsen/SoundScan. The songs are ranked by their sales totals as of this week. I show where the songs peaked on the Hot 100. I also indicate the songs that won Grammys and/or received Grammy nominations for Record or Song of the Year.
Post Script I: Here are the next five songs in line: Rihanna's "Disturbia" (3,960,000), Pink's "So What" (3,947,000), Lil Wayne featuring Static Major's "Lollipop" (3,937,000), Journey's "Don't Stop Believin'" (3,920,000) and T.I. featuring Rihanna's "Live Your Life" (3,909,000).
Post Script II: Nielsen SoundScan first posted an all-time Digital Songs chart on its site a little more than two years ago (on July 6, 2008.) Only five songs that were ranked in the top 20 on that first recap are listed in the top 20 on the current one. That of course means that 15 songs have tumbled out of the top 20. I'm going to list them all. After each title, I show the song's ranking on that first all-time chart, followed by its ranking on the current one.
First, the five "keepers": "Low" (#1 to #2), "Crank That (Soulja Boy) (#2 to #12), "Apologize" (#3 to #8), "Stronger" (#6 to #17) and "Bleeding Love" (#10 to #20).
Now, the 15 "goners": Plain White T's "Hey There Delilah" (#4 to #29) Fergie's "Big Girls Don't Cry" (#5 to #35), Rihanna featuring Jay-Z's "Umbrella" (#7 to #34), Justin Timberlake featuring Timbaland's "SexyBack" (#8 to #38), Alicia Keys' "No One" (#9 to #42), The Fray's "How To Save A Life" (#11 to #37),
Avril Lavigne's "Girlfriend" #OOP (#12 to #48), Colbie Caillat's "Bubbly" (#14 to #46), Akon featuring Eminem's "Smack That" (#15 to #59), Fergie featuring will.i.am's "Fergalicious" (#16 to #63), Sara Bareilles' "Love Song" (#17 to #49), Gwen Stefani featuring Akon's The Sweet Escape" (#18 to #67), Nickelback's "Rockstar" (#19 to #39) and Lil Wayne featuring Static Major's "Lollipop" (#20 to #23).
http://new.music.yahoo.com/blogs/cha...JNvbzOwIwPwiUv
she's 3 times in the list 
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