I am - and have always been - a fan of USPS, however I think this is the perfect example of "how to lie by using statistics". The chart referenced by the second link advertises a 4.7% increase in "International (includes letters, cards, flats, and extra services)". And they do not mention how that percentage increase is calculated.
Which makes the information of very little use to me, since I cannot understand what the MEANING of it is.