You've Written Over Four Thousand Songs

My mother was a poet and a song writer. She wrote a style of music called bolero. So as soon as i could get up on the piano bench, i started banging on the piano and creating my own melodies. To me, it's just second nature. You've written so many songs. Would you say that large percentage of what you write is usable and goes on to be successful? Or is there more work than that that goes in to find in those particular smashes?