The autograph has several giveaways - to give you a few pointers.
1. Bowie signed very very few 2009's - it was the height of his first wave of cancer, the ones he did sign were limited edition books and prints for friends only (ie Geoff MacCormack).
2. He had (with the rare exception) dropped writing the full 2000 in 20008 (ie only writing '08)
3. As Eric says all the numerals are wrong both characteristically and size-wise.
It would fool quite a few as the main signature is not that bad but as Eric identified, it ain't real.
Hi Mark! :) Agreed, the main body of the graph is not bad, the forger is observant re form to to year (more or less) but makes errors as you mentioned re date etc and can not smoothly execute.