Note: The chart has been updated 7/14/2017 to include up to 2015 vintages.
In 2007 Hugh Johnson said that vintages don't matter anymore and I pretty much agreed. His statement was more of a rebuke to the wine trade and its use of snobbery and insecurity of consumers to inflate prices. This has been especially true of top Bordeaux wines but after a string of difficult years, there has been less emphasis on using vintage as a marketing tool.
This is exactly why we should pay at least a little more attention to vintages. The world is getting warmer but more importantly, the weather is getting more erratic. Our vintage chart is deliberately done in broad strokes on a 1 to 5 scale mainly because it's impossible to be precise for an entire region. Unfortunately it can't do a very good job showing a mixed vintage, so when you see any vintage less than a 4, it makes sense to be a little cautious especially when purchasing expensive wines.
If you would like to read more about how a vintage chart is made, here's the original story on The Making of a Vintage Chart.