It just depends on the airport, more Airline traffic generally would bring more jetways. But that can contradicted, many Airports that have Airline traffic don't have any jetways at all, such as San Angelo.
What I don't understand is how Airports with only one jetway run more than one Airline out of one jetway. It would just get confusing.
I suppose a better question would be, How many airports have only one Jetway and service more than one airline?
(I know i'm ranting somewhat) But what I also find amusing is small airports that have 3 or 4 runways.
