Is twitter gaining on facebook?

In spite of the headlines, and the feeling I get that "everybody" is on twitter - highschoolers, college kids, brands and wannabe-brands, this is what a major web-traffic data site has to say about that question:

Facebook remains heavily dominant over twitter

Facebook, with its #2 ranking and 45% reach, maintains a 5-1 lead over twitter (about 9% average reach for Q1 2013 and ranked 10th most popular site in the world).  It's what the data says.  Now one could question the sample e.g. who uses the alexa tool?