Well, the fact that a good number of people do not know about him does not mean he’s not popular and getting popular by the day.
There are many people of that age (35-40) which probably have teenage kids already knowing about Deadpool, and now this movie gives a complete exposure to the character.
People in Italy do not even know who Archie is, or most of the DC Comics less known characters (given the discontinuing nature of DC publications here) but most people will be exposed to Deadpool on a movie level, so they get to know the character and could discover the comics later on.
Also, most people UNDER 35 in the USA barely know the richness of Walt Disney‘s comics universe, as opposed to most people in Europe, of all ages. This is a fact.