One point to make:
Notice that "Byzantine Catholics" and "Roman Catholics" are listed separately. "Roman Catholic" is a borderline misnomer, a epiphet that the Catholic Church chose not to fight because Church Fathers did historically call the Catholic Church "Roman." This was because it was recognized that the Church was NOT universal among the barbarians. Hence, Roman modified Catholic, making "Roman Catholic" mean "universal in the civilized world."
In English-speaking countries, however, "Roman" has come to simply mean a synonym for "popery," with the connection of the Catholic Church to Rome. This is a misleading use; the Vatican is deliberately outside of Rome, in exile until the second coming of Christ. (Hence, "Peter the Roman," at the end of St. Malachi's list of Popes, signifies that such a Pope would rule at the second coming.)
I believe what the State Department intends to do is contrast the Latin Catholic patriarchy from the Byzantine Catholic patriarchies. Alternatively, they could also be using Byzantine in a way alien to the Catholic Church to refer to the Eastern Orthodox religions. That would be even more problemmatic, however, since the Catholic Church uses the term, "Byzantine" to mean, specifically, to those Eastern patriarchs which are loyal to the Pope, and, hence, "Roman" Catholic.
I read the same thing and presumed that the "2001 census" was conducted by the Republic of Slovakia and not the U.S. State Department. The categories come from Slovakia, don't they?