id	keyword
dem-5672	trade
dem-5672	model
dem-5672	gravity
dem-5672	time
dem-5672	effects
dem-5672	countries
dem-5672	costs
dem-5672	variables
dem-5672	importer
dem-5672	country
dem-5672	remoteness
dem-5672	gravity model
dem-5672	results
dem-5672	flows
dem-5672	distance
dem-5672	estimation
dem-5672	resistance
dem-5672	terms