if you read through the article, you'll see that solar capacity more than doubled from 2009-2010. it would be nice if it included previous growth, which actually was similar. but this is more about the future based on what is happening now and expected in the future... i'm sure they used the previous years' data though & showing those data in such a graph would be useful as well. however, the site covers that regularly, so I think the regular readers are quite familiar with the info.