PDF
9,983,432
ePub
8,926,670
Kindle
3,826,113
eReader
2,923,618
FictionBook
1,991,660
Plucker
1,597,846
Palm Doc
1,591,886
Large Print PDF
1,369,757
Mobipocket-mobi
1,315,641
iSilo
1,211,164
Plain text
886,246
RTF
880,635
Cellphone (.jar)
767,065
Sony (Librie, Reader)
571,526
Mobipocket
467,560
Custom HTML
326,528
Microsoft LIT
278,338
iPod
143,363
zTXT
22,386
Rocketbook
18,279
iPhone Books.app
5,754
TCR
3,738
Newton
2,720
Total: 39,111,925 downloads
since June 1, 2009, or thereabouts.