Average roundtrip airfares on all U.S. routes reached a 13-year high in the second quarter, up 8 percent, and PHL followed the trend, with fares up 8.5 percent, compared with the same 2007 period, according to goverment data reported today. PHL's average fare continues to be below the national average by a few dollars ($352 vs. $338 at PHL). Read a brief news story here. To see the big picture, and 13 years of data for PHL and other cities, go to a BTS Web site link. That's where you can see the dramatic effect the arrival of Southwest at PHL had on fares. For years before 2004, the airport was way above average, and since it's been below average.