ok how bout 2012?
http://www.dhs.gov/sites/default/files/publications/ois_ill_pe_2012_2.pdf
its 59% mexican...
of course these are estimates..
anyone can cross the border it doesnt take any great skill, its mostly luck... the wall doesnt work for an example as to why putting your trust in a wall doesnt work look at the Maginot line in france it must be in combination of several things.. personally i think you put land mines between here and there motion detectors and monitor and treat every crossing as a hostile act.. then these will stop rapidly... hell i think we should use live fire drones to protect our border... we start killing people as they cross our border, it will stop.
hell if you make it over or around the wall, past the motion detectors through the mine field, past the drones dropping bombs from above... then hell we will give you citizenship you earned it... otherwise we have a legal way for you to get into the country you may partake in that freely...