The Obama administration had the lowest average annual number of deportations of any presidential administration since the early 1970s, according to a new report by the Center for Immigration Studies.

That is primarily because the number of deportations of illegal immigrants not caught at the border have plunged by 73 percent since Obama took office.

Under President Obama, the Department of Homeland Security has said that 2.7 million illegal immigrants have been "removed or returned" to their country of origin. The figure is often cited to refute claims that Obama has been soft on immigration. However, the Center for Immigration Studies, which favors restrictionist immigration policies, argued in a report released this month that the figure is misleading because it focuses on people turned away at the border and those who voluntarily return.

"Counting only removals as deportations presents a misleading picture of the level of enforcement. Removals are just one form of the deportation process that can be executed by any of the three DHS enforcement agencies [Immigration & Customs Enforcement, Border Patrol and Customs and Border Protection]," the CIS report stated. "The Obama administration has completed a total of 5.3 million deportations, counting both interior and border cases. That is a little over half the number of deportations under the George W. Bush administration. The true record for deportations was set by the Clinton administration, which completed 12.3 million deportations."

Looking at annual rates, Clinton averaged 1.5 million deportations a year, while Bush had 1.3 million. Obama had an annual rate of just 664,000.

The total deportations for Presidents George H.W. Bush, who served one term, and Ronald Reagan were 4.1 million and 8.2 million, respectively. President Jimmy Carter, also a one-term president, had 3.6 million deportations. Bush and Reagan had annual rate of just over 1 million deportations, while Carter's was just under 1 million.