Adele, Gotye, among year's biggest sellers ... so far

With the first six months of the year now complete, Nielsen and Billboard report that Adele, Gotye and the late Whitney Houston are among the artists with the top-selling songs and albums of 2012 so far.

Adele's chart-topping sophomore set, "21," is the best-selling album and best-selling digital album of the year to date, with sales of more than 3.5 million and 876,000, respectively. Goyte's breakthrough single, "Somebody That I Used to Know," featuring Kimbra, sold more than 5.5 million digital songs, helping to boost digital sales of his debut album, "Making Mirrors," to just over 300,000 units.

The iconic Whitney Houston, who died of accidental drowning in a Beverly Hills hotel in February, holds the top spots on the best-selling overall catalog album and digital catalog album with her 2000 release, "Whitney: The Greatest Hits." More than a million albums -- both physical and digital combined--have sold since the start of 2012, particularly following her unexpected death.

In March, Lionel Ritchie unveiled his 10th studio effort, "Tuskegee," which features duets with a handful of chart-topping country musicians including Willie Nelson, Rascal Flatts and Kenny Chesney. That album currently stands as the second highest-selling album of the year and has outsold Ritchie's last three releases combined.

So far this year, Justin Bieber's "Believe" has had the biggest debut, selling 374,000 copies its first week in stores, and YouTube sensation and Bieber-supported Carly Rae Jepsen has landed the most streaming music plays (54.5 million) with her debut single, "Call Me Maybe."