By CNN Library

(CNN) - On Monday, a bipartisan group of senators announced a new immigration effort in Congress before a scheduled speech by President Barack Obama on immigration reform.

Here are facts on immigration, by the numbers:

- U.S. Immigration and Customs Enforcement detained 409,849 undocumented immigrants in 2012.

- The estimated total number of undocumented immigrants in the U.S. was 11.5 million in 2011.

- The number of people who obtained legal permanent resident status in 2011 was 1,062,040. The top 10 countries were Mexico, China, India, Philippines, Dominican Republic, Cuba, Vietnam, South Korea, Haiti and Canada.

- 59% of undocumented immigrants are from Mexico (6.8 million). The other top countries are El Salvador (660,000), Guatemala (520,000), Honduras (380,000),  China (280,000), Philippines (270,000), India (240,000), South Korea (230,000), Ecuador (210,000)  and Vietnam (170,000).

- 2.8 million illegal immigrants reside in California, while 1.8 million live in Texas.

- In the first half of 2012, 41 legislatures enacted 114 bills and adopted 92 resolutions that address legal immigrants, migrant and seasonal workers, refugees or undocumented immigrants.

Asians, more than Latinos, are largest group of new arrivals in U.S.

Timeline

2008: The Department of Homeland Security apprehends 792,000 foreign nationals - 88% of those were natives of Mexico. Immigration and Customs Enforcement apprehends 379,000 people.

2008: DHS removes 359,000 undocumented immigrants from the U.S., sending 69% of them to Mexico, 8% to Honduras and 7.7% to Guatemala.

2008: 811,000 illegals accept offers to return to their home countries without being forcibly removed.

2008: 97,100 criminals who are also undocumented immigrants are removed from the U.S. by DHS; 36% of those were convicted of drug-related crimes.

2009: The number of children born to at least one unauthorized immigrant parent is 350,000 - 8% of all U.S. births.

2010: Number of unauthorized immigrants in the U.S. labor force is 8 million - 5.2% of the labor force.

2010: 1.04 million people receive legal permanent resident status - 139,120 of them were born in Mexico, 70,863 in China and 58,173 were born in the Philippines.

2011: ICE removes 396,906 undocumented immigrants from the U.S. - 216,698 (nearly 55%) have been convicted of felonies or misdemeanors, the largest number in the agency's history.

April 23, 2012: The Pew Hispanic Center announces that the net migration from Mexico to the U.S. has stopped and possibly even reversed. They note that from 2005 to 2010, about 1.4 million Mexicans immigrated to the U.S. and about 1.4 million Mexican immigrants and their U.S.-born children moved from the U.S. to Mexico.

Sources: Bureau of Labor Statistics; Department of Homeland Security; National Conference of State Legislatures; Pew Hispanic Center; U.S. Immigration and Customs Enforcement