Why do I even bother?

Spotted in DC in an article about the rupee (italics mine):

In nominal terms, it has fallen from Rs 39.27 to the US dollar on January 15 to Rs 51.10 to the US dollar by March 3 -- a decline of more than 30% in less than two months.

The time it took for the rupee to fall 30% is actually 13 months, since the January 15 refers to 2008, not 2009. It wouldn't have mattered so much if this was from a regular news item (what with reporters facing deadlines and all), but the sentence in question is from the first paragraph of an op-ed piece, where one would assume more care would be taken to ensure accuracy.