Simplify the following text for a Grade 10 native English-speaking person.
Original: In 2000 , Joel Whitburn , a Billboard Magazine pop music researcher , named her the most successful female songwriter of 1955-99 , because she wrote or co-wrote 118 pop hits on the Billboard Hot 100 .
Simplified: In 2000 , Joel Whitburn , who writes for Billboard Magazine , named her the most successful female songwriter of 1955-99 , because she wrote or co-wrote 118 pop hits on the Billboard Hot 100 .