As far as PR is concerned, I've seen demographic/biological data that shows that 60% of Boricua are "of color." Judging from the folks that I've met on the island or on the mainland, that sounds about right. The average Puerto Rican has more European blood than African blood (unlike Dominicans, who generally are the reverse), but, nonetheless, about 40% can be characterized as "pure white" according to most studies I have seen on the island. Puerto Rico was 50-55% white +/- under Spanish Governance in its Censuses. The present 80% "white" claim of the 2000 Census is based on wannabe status, and a desire to not be seen as black, given what Puerto Ricans observe of American culture. The demographic shift in self-idenitification took place mostly between 1910 and 1940.
"The demographic shift in self-idenitification took place mostly between 1910 and 1940."
I don't think it was a shift in self-identification as much as a change in the way the census was conducted. The Spanish would send someone to each home, take a look at each resident, ask pertinent questions, and mark whichever race he thought each person was. That was still the case in the 1910 and 1920 censuses run by the U.S. government. However, at some point, self-identification became the norm, and light-skinned mulattoes sure as heck weren't going to say they were black. Other factors contributing to the change from 1910-1940 could be (i) the race of the person conducting the census (probably more racially mixed Puerto Ricans conducted censuses as the decades went by) and (ii) the reduction of choices for the census (in the 1920 Census, they still allowed "mulatto" as a choice).