The powerhouse vocalist has earned more than 30 top 10 hits as a soloist and in a group. We hope this week’s chart news can make Taeyeon a bit more “Happy.” The K-pop superstar returns to Billboard‘s World Digital Song Sales chart with “Happy” entering at No. 9 this week. The nostalgic R&B-pop track sold 1,000 downloads in the week ending May 8, according to Nielsen Music/MRC Data. The No. 9 debut for “Happy” marks Taeyeon’s 15th top 10 entry on World Digital Song Sales to date. Since making her first solo appearance in 2014 with the song “Breath,” sung alongside fellow K-pop singer Jonghyun, Taeyeon has been a consistent chart force. The star earned her highest-charting single in early 2016 with “Rain” ...