Apple announced Tuesday that more than three billion songs have been purchased and downloaded from the iTunes Store. The store has a catalog of over 5 million songs, 550 television shows and 550 movies.

The most significant thing about this is the growth curve and especially the pace at which Apple reached its latest billion-song threshold. It took the company a little less than three years to sell the first billion iTunes downloads. Then it took less than a year (11 months) to sell the second billion. Now, just over six months later, the store has passed the three-billion song mark.

Looking at it as precisely as possible, if we assume that the two and three billion song targets were hit the same day as the press releases went out (January 9, 2007, and July 31, 2007, respectively), that means it took 203 days to sell one billion songs. That means the Store had to average about 4,926,108 song purchases per day, or 205,255 per hour. Breaking it down even further, that’s 3,421 songs sold per minute, or an astounding 57 songs sold every second for those 203 days!

Regardless of the portion of the market that’s an extra 3 billion dollars revenue on the balance sheet (1 song = about $1.00). I believe Apple makes between 10 and 20 cents per song profit… So that’s 300 to 600 million dollars in profit. Thanks iTunes Store!