A new report released by the U.S. government reveals that the number of deportations of undocumented immigrants declined for the third consecutive year.

Since President Barack Obama's election in 2008, more than 2.4 million immigrants have been deported. However, the deportation rate has steadily declined in the last three years.

The data, which was obtained by The Associated Press, shows that the Obama administration deported a little more than 231,000 immigrants who were living in the U.S. illegally during the past 12 months, ending on Sept. 28, 2015. That is the lowest number of immigrants that have been forcefully removed from the country within one year since 2006.

The deportation rate has also dropped by 42-percent drop since 2012, which is the year that deportations peaked at over 409,000.

Although deportations of criminal immigrants have also fallen to the lowest levels since Obama took office, the number of criminal immigrants deported in relation to overall immigrants deported jumped from 56 percent to 59 percent.

The decline in criminal deportations comes as a surprise since Homeland Security Secretary Jeh Johnson directed immigration authorities, last year, to focus on finding and deporting immigrants who may pose a threat to national security or public safety. Those who have serious criminal records or recently crossed the Mexican border were also targeted.

The decline, however, could be an indication that the government has been failing to find criminal immigrants in the U.S., or that fewer undocumented immigrants had committed serious crimes that could justify deporting them.

According to the Homeland Security, the steady decline is a result of the changing demographics at the Mexican border since more immigrants are from countries other than Mexico. In addition, there was a spike in unaccompanied children and families caught trying to cross the border illegally last year.