In that case I would suggest changing a couple and reviewing any changes in rankings as a result. This is one to approach slowly.
Not sure how you have access (are they paid?), but by changing a large amount of links at the same time it may alert Google to some suspicious activity. Large changes in anchor text can be a sign of changes to bought links.
Personally, I wouldn't change them all either. Even though the year is wrong, there's still going to be benefits. e.g. if you are trying to rank for "holiday in new york 2013", your rankings will still benefit from keywords saying "holiday in new york 2012".
Take it steady and keep reviewing the results, but bear in mind you may be better focusing your efforts on building new links with new anchor text.
Hope that helps,
Ben