1997, 1998, 1999, 2000
flight's origin
flight's destination
route identifier
distance, in miles
avg. passengers per day
avg. one-way fare, $
fraction market, biggest carrier
log(distance)
=1 if year == 1998
=1 if year == 1999
=1 if year == 2000
log(fare)
ldist^2
= bmktshr
log(passen)