One of the most reliable ways to gauge the passing of time during the past few decades has simply been to look at whatever James Bond film has been released recently. If your 007 is tall, dark and Scottish, it must be the '60s. If Bond is older, refined and slightly cartoonish, it's the '70s. And if MI6's premiere special agent is tough-as-nails, brutish and violent, you're living in the 21st century.
However, what sometimes throws a wrench into this pattern is if Bond films aren't being reliably produced. The gaps in production can create strange eras in the franchise, such as the period from 1989 to 1995 that saw nothing released between Licence to Kill and GoldenEye.
Yet that gap is different than the ongoing one. The transition from one actor to another (in that case Timothy Dalton to Pierce Brosnan) requires a delicate touch and plenty of attention from filmmakers. At the moment, pending the release of Skyfall, it has been four years since the last Bond picture despite the fact that Daniel Craig continues to reprise the role of 007.
According to MTV News, Craig is getting a little antsy himself. To hear him tell it, these movies would come out like clockwork every year or two, the way they did in the '60s and '70s. We can't agree with you more, Daniel -- so long as Skyfall ends up being as amazing as it looks.