More than 40 million immigrants live in the U.S., representing 13 percent of the population. In recent years, immigration reform has been an especially hot topic.

Following are some immigration facts from www.nbclatino.com and www.cnn.com:

• Fifty-nine percent of undocumented immigrants are from Mexico.
• In 2012, U.S. Immigration and Customs Enforcement removed 409,849 undocumented immigrants.
• The number of undocumented immigrants in the U.S. peaked at 12 million in 2007.
• Of all immigrants in the U.S., 29 percent came from Mexico; about 25 percent from South and East Asia; 9 percent from the Caribbean; 8 percent from Central America; 7 percent from South America; 4 percent from the Middle East; and the rest from elsewhere.
• California is home to the largest share of U.S. immigrants—27 percent of the immigrant population.
• In 2011, more than 1 million people got green cards.
• The U.S.’ first wave of immigration took place from 1820-1870, when people emigrated mostly from northern and western Europe; the current wave is the U.S.’ fourth wave, which began in 1965 with the end of immigration limits based on nationality.
• In 1960, fewer than 1 million people in the U.S. were born in Latin America; by 2012, there were 21.2 million.
• In 1960, 75 percent of immigrants in the U.S. came from Europe; by 2010, 80 percent came from Latin America and Asia.
• The fence between the U.S. and Mexico runs on and off for 651 miles along the 1,954-mile border.
• Twenty years ago, fewer than 4,000 Border Patrol agents worked along the Southwest border; there now are 18,500 agents.
• Since 1986, more than 4 million noncitizens have been deported.

This Web exclusive information is a supplement to Capitol Hill.