And it's the folks not on the ground that make the official reports the government uses to determine funding, and the press releases that make the headlines. I'm sure the guys on the ground have an excellent understanding of how effective they're being, but privates don't write press releases. Officially, according to the reports, you only catch 10%, whether you catch 2 or 2 million doesn't matter, the official estimate are that the number of guys you catch is 10% of total attempted illegal crossings.
I've been doing this for 7 years and have never seen an official report stating a 10% apprehension ratio.