That's much lower than the 81% success rate that Homeland Security cited publicly using a different counting method. In terms of people, 170,000 got away from the Border Patrol during fiscal 2015, 210,000 the previous year and 1.7 million in 2005. The government now spends $14 billion annually on border security. The Border Patrol achieved an 11-point improvement in 2014 after years of slow but steady gains. Homeland Security approaches the job by tracking physical evidence, such as footprints in the desert and other signs of human presence, and by agent sightings.

Source: Los Angeles Times October 07, 2016 01:59 UTC