View the track charts.
View the artist charts.
I won't inform you as to the number of downloads required to gain this height (charts are generated on the number of downloads from unique IP addresses) but it wasn't a great deal compared to the general music industry.
I heard recently that a long time again in order to get to number one in the single charts (back when a single was sub $1 and on vinyl with a real actual b-side on the OTHER SIDE!) you needed to sell 700,000 records. Recently Mr. different-coloured-eyeballs Manson managed to get platinum and number one with 70,000 sales.
I also heard from a friend that Coke could purchase the entire music industry, make all music free and write it off as advertising. Ouch.