Charts showing the the immigration lottery in the US is worth a look.

David J. Bier sums up the situation at the Cato Institute:

Legal immigration is less like waiting in line and more like winning the lottery: it happens, but it is so rare that it is irrational to expect it in any individual case.

[…]

… the system is restrictive compared with other countries. The United States ranks in the bottom third of wealthy countries for foreign-born share of the population. Even if it accepted 70 million immigrants tomorrow, it would still not surpass the likes of Australia.

Immigration benefits the United States, so there is no reason to place hard caps or strict categorical limits. Moreover, enforcing restrictive laws is costly and results in illegal immigration. The entire legal immigration system is actually designed not to be followed by most people, but to keep most people out. America should return to its system of openness that reflects U.S. traditions and benefits the country.