According to the 2010 Census, Hispanics in America have now surpassed 50 million. That is 16.1 percent of the total population. I've listed the 2000-2008 GSS percentages for large ethnic groups (sample size = 11,840) :
Percent of total U.S. population
Hispanic 16.1 (2010 Census)
American only 3.0
Hispanics are now the largest group. Demographically speaking, America is more Hispanic than it is German, black, Irish, English, etc. On the other hand, "Hispanic" is a contrived category. If we focus on Mexican Americans only-- a real ethnic group--they are two-thirds of Hispanics which would put them currently at 10.6 percent of the U.S. population. That is larger than any other ethnic group except for Germans. And as big as they are, Germans do not stick out in American society; Mexicans do.
Demographers project that Hispanics will be one-third of the population by 2050. (That will only happen if we let it.) Considered as an ethnic group, they will dwarf every other ethnicity. They might become the monster ethnic group, but then again, their growing presence, along with that of other non-white immigrant groups, might forge whites into a real, monster ethnic group.