Technically it could be either, but if it is written that way then that will usually be referring to 2003. Most often if it is in approximately the first half of the 20th century or before, it will be written with a 4 digit year (ex: 1931), and anything after that point will sometimes be written with a 2 digit year and sometimes with a 4 digit year. However this line does blur a bit around the middle of the 20th century, so if you see something with a 2 digit year it is always a good idea to look at the context as well.
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