Lugols, Iosol or any iodine solution: Shelf life

Does anyone have an opinion on how long iodine solutions last? I have a bottle of Lugol's that I purchased in May of 2010. Do you think that is is still effective? I have read in several places on the internet that the bottles last up to a year, but I am unsure if the source is reliable.

Thanks.

By "bottles last up to a year" are you sure they don't mean it as in, the iodine will last you a year if you use it every day? Rather than last a year before it "goes off"?

A quick Google found me a few sites saying it should last 5-10 years. I had a bottle of Iosol for around 8-9 months before I used it and felt benefits, I would say it's probably fine.