Reference non-measures in calculations and agents?

Hello!

I have some dummy data that contains (1) Country (2) Airline  (3) Passengers

I want to hide all the countries that only has one Airline associated with it.
However, when I try to do an allcount (or a count as well), it won't let be choose the two first columns. d1 and d-1 both reference the passengers column. 

Is there a way to count the amount of Airlines a country has, and then filter based on that?

Below is a screenshot of the dummy data


 Country                                                                          Airline Code                                   #passengers