Grammatically, the tense is present.
Depending on when the document was written, by the middle of 2011 could indicate a future meaning, but it is unlikely that the author means that his numbers will, at some future date, all of a sudden, become up to date!
Most likely, the present here is used as a historical present, meaning that the figures were up to date at the indicated moment. They may not be up to date now, as things may have changed between publication and the time of reading.
Such a disclaimer is very common when dealing with statistics. You give numbers, present graphs, but you make very clear that the information that you are presenting was correct and checked to be correct only at a certain moment. If, after publication, new facts emerge, you have (logically) not incorporated that future information onto your presentation. That may sound like a ridiculous disclaimer, but without it, you may raise the expectation that your numbers, once published, will always be kept up to date.