"[T]oday’s system now allots 7 percent of each visa category per country. For example, the law allows for 366,000 family- and employer-sponsored visas. That means up to 25,620 such visas (7 percent) are allowed for each country, whether you’re trying to get in from China (population: 1.34 billion) or New Zealand (4.4 million).
Rather than end discrimination in immigration, that oversimplification has resulted in confusion and logjams. The exemption for immediate relatives (there are no quotas for spouses and underage children of citizens) has inflated those immigration numbers by a quarter-million per year. There are certain visa categories in which employers cannot bring in workers from China, India or the Philippines, no matter the need. In family preference categories, Mexico currently has 93,431 people waiting for its 7 percent (1,638) of F1 slots.
That translates to a wait of 57 years for the adult children of American citizens. In one family preference category (F2B, unmarried adult children of legal residents), the wait is 109 years.
It seems clear that to be effective, comprehensive immigration reform mustn’t miss an obvious target: revising the 7 percent system." - Dallas Morning News Editorial, Feb. 17, 2013.