When I do peer review, I want to see at least half of the citations from within the most recent five years.
I count from the beginning of the year, so for now, I would say 2011 to present. After January 1, I will say 2012 to present.
Certainly there are important studies from earlier years, but you want to show that you are basing your work on the most recent literature. So I think around 50% is a good rule of thumb.
On the one hand, I agree with Michael. On the other, I do not. The 5-year 'rule' is often adopted - but it depends on context. If it's a primary study manuscript that wants to report a 'gap in knowledge' then the 5-year rule is logical. If it's perhaps a more conceptual/theoretical/philosophical manuscript - then the older, seminal literature will often govern the content. Even with primary studies, I would not be as strict as Michael and 'count the date' of 5-years - and then 'that is it'.
I agree but I have a couple of papers refused because of old papers although the topic was review of literature which necessitate all current literature.
Hera - that's part of the problem. Some authors, editors,reviewers etc take the 5-year rule too literally!! I repeat again that it depends much more on the manuscript context - than some 'assumed' rule of thumb.