By Bonnie Stiernberg Perhaps we shouldn’t be surprised at this point whenever another new study confirms our suspicions about how far the music industry still has to go to achieve gender parity. Progress for women in the historically male-dominated industry has been depressingly slow, and according to new research, there’s still plenty of room for improvement. For the past five years, the USC Annenberg Inclusion Initiative has released an annual “Inclusion in the Recording Studio?” report analyzing the gender makeup of all the artists, songwriters and producers responsible for all of the songs…