Question: Which American singer-songwriter that had 15 number one singles in 2015 helped Shakira write Medicine?
Sentence (from "Medicine (Shakira song)"): Featuring guest vocals from American country music singer Blake Shelton, the song was performed on the 49th Annual Academy of Country Music Awards on April 6, 2014, and spent one week on the country charts at number 57 from unsolicited airplay.
Relevant evidence: No