Border Patrol does report the numbers and nationalities of the illegals.
http://usgovinfo.about.com/od/defenseandsecurity/a/otmaliens.htm
Easy report to read. You can go to the source documents if you wish.
"Since September 11, 2001, DHS has reported a 41percent increase in arrests along the Texas/Mexico border of Special Interest Aliens," states the report. "From FY2001 to March 2005, 88 percent of Special Interest Alien apprehensions for both the Southwest and Northern borders occurred in Texas."
An increase of 88% from 2001 - 2005 ..... wonder what it's been since?