The number of undocumented immigrants in the United States dropped from 12 million to 11.1 million, between 2007 and 2011, according to new Census Bureau data.

The analysis from the Census Bureau’s Current Population Survey shows that 28 percent of immigrants in the United States are undocumented, 31 percent are legal permanent residents, and 37 percent are naturalized United States citizens.

The economic difficulties in the US and stronger border enforcement are believed to be the reasons for this drop.

These results have surfaced as the Republican Party have begun see the need for immigration reform in the United States following Mitt Romney’s failure to win the Hispanic vote.

Earlier this week, former Republican President, George W Bush, called on the US government to begin a discussion on immigration reform with a “benevolent spirit”. He added “Immigrants have helped build the country that we have become, and immigrants can help build a dynamic tomorrow.”

Read more: George W Bush calls for a ‘benevolent spirit’ during US immigration reform – VIDEO

Jose Antonio Vargas, 31, a journalist from the Philippines spoke to the Associated Press on the issue of immigration reform. He said “The priority now is to push a vigorous debate about the undocumented people already here.”

Vargas is part of the campaign group Define American, along with the young immigrant group United We Dream.

He added "We want to become citizens and not face the threat of deportation or be treated as second class.

"This conversation is a question about how we as a nation define who is an American…If you want us to pay a fine to become a citizen, OK. If you want us to pay back taxes, absolutely. If you want us to speak English, I speak English. But we can't tread water on this issue anymore."

A senior demographer at the Pew Research Center and a former Census Bureau official, Jeffrey Passel, said U.S. immigration policies will have a significant impact in shaping a future United States labor force. This labor force is projected to shrink by 2030 as aging white baby boomers begin to retire. However South American immigration, which helped to fill needs in farming, home health care and lower waged jobs, has leveled off.