"Like Gomez, more than a third of El Pasoans have little or no English skills, according to the Census 2000 Supplementary Survey data released last week.
Nearly four in 10 El Paso County residents who were surveyed said Spanish was their dominant language, while a similar proportion said they communicated in two or more languages. One in five said English was his or her dominant language.
About one-fourth of El Paso County's population was born outside the United States, compared with 14 percent across the state and 11 percent across the nation, according to the Census 2000 Supplemental Survey.
http://www.borderlandnews.com/Census/1125language.shtml
Read what you posted...4 in 10 said that Spanish was their dominant language.
My parent's would answer the very same way, it doesn't mean that they don't speak English, they speak it quite well, but Spanish is their dominant language nevertheless.
Then another 4 in ten or so admitted to communicating in two or more languages. Again, it doesn't mean that they don't speak English.
Only 1 in 5 said that English was their dominant language.
By "dominant language" they probably mean the language that they dream, and think in. That takes a long time to happen.
I don't see where you proved your point here.