"...continue to think of themselves as Catholic."

Quite true. In 2008, Emeritus pope Benedict attempted to point out (when addressing Catholic University in Washington, DC) that defining Catholic identity is anything but a straightforward process; that neither statistics, church going, nor orthodoxy are the sole measures; that there are layers and layers of intangibles, ambiguities,  and allegiances within a person that indicate a "Catholic identity." Michelle Dillon in CATHOLIC IDENTITY: BALANCING REASON, FAITH AND POWER (Cambridge, 1999) notes this and that religious identity, especially Catholic identity, is still in its infancy, especially in trying to understand those who "think of themselves as Catholic" (and really are, as far as she and the pope are concerned). However, when we talk about numbers, current Catholics and ex-Catholics, we are MAINLY talking about DATA, what people say to pollsters. Pollsters want ONE answer: yes or no to question: are you Catholic? Yes or no!