Steve Jobs stands by a projection of the iTunes website as he launches iTunes Music Store in 2004 in London. The iTunes store revolutionized music, allowing users to buy and download albums or individual songs from a library of 700,000 songs.
Earlier this week, Apple chief Tim Cook announced a new record of 575 million iTunes accounts. Since Apple announced in 2009 it had reached 100 million, that means that Apple would have had to add an average of 500,000 new iTunes accounts per day in the last three years.
Asymco's Horace Dediu plotted out the numbers since 2009 to calculate its growth rate, according to AppleInsider. If the numbers are correct, Apple will add another 100 million accounts by the end of 2013.