In 2001, she became the first African-American woman and second woman songwriter to win the Pop Songwriter of the Year award at the American Society of Composers, Authors, and Publishers Pop Music Awards. Beyoncé was the third woman to have writing credits on three number one songs ("Irreplaceable", "Grillz" and "Check on It") in the same year, after Carole King in 1971 and Mariah Carey in 1991. She is tied with American songwriter Diane Warren at third with nine songwriting credits on number-one singles. (The latter wrote her 9/11-motivated song "I Was Here" for 4.) In May 2011, Billboard magazine listed Beyoncé at number 17 on their list of the "Top 20 Hot 100 Songwriters", for having co-written eight singles that hit number one on the Billboard Hot 100 chart. She was one of only three women on that list.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Who listed her at number 17 in their list of  Top 20 hot 100 Songwriters?
Billboard magazine