Yea, that doesn't seem like that useful of a number, since Frankfurt is a fairly major layover airport for international travel.
I guess the more specific question would be how many Germans fly to elsewhere in Germany or Central Europe vs. taking a train. I generally have to either do a long car trip or a flight to get around in the US outside of some specific corridors. Presumably most of Europe has the option to take the train instead, but are they?
And yet layover flights are decreasing since the 2 engine restriction was "lifted". A 787 can fly non stop for as long as would be comfortable for someone to be on a plane.
But there’s still a connection/hub-and-spoke system. You could fill a 787 with enough fuel to fly from Columbus, OH to Venice, but you couldn’t fill it with enough people to make it make sense.
And airlines usually charge more for direct flights (price discrimination), so for leasure long-haul travel it's fairly common for Europeans to have a flight with stopover, even if there's a direct connection available.
I guess the more specific question would be how many Germans fly to elsewhere in Germany or Central Europe vs. taking a train. I generally have to either do a long car trip or a flight to get around in the US outside of some specific corridors. Presumably most of Europe has the option to take the train instead, but are they?