Airlines charging for bags probably won’t go away anytime soon. What’s interesting, is how little it is of their total revenue.

Here’s more from Fortune.com:

Airlines in the United States made more than $4.2 billion in baggage fees, accounting for 2.5% of revenue last year, though the industry still saw overall profits significantly decrease.

Baggage fees were the highest area of profit growth, according to a release Tuesday from the Department of Transportation. Baggage-fee profit went up 10% in 2016 compared to 2015, an increase of about $372 million, according to the DOT.

The airline with the highest baggage-fee profits, American Airlines, made more than $1 billion in 2016, according to the report.