Washington (CNN) In his first year in office, President Donald Trump's administration's arrests of immigrants -- especially those without criminal convictions -- were up substantially, but actual deportations lagged behind his predecessor, according to statistics released Friday.

The jump corresponds to Trump's central pledge to crack down on illegal immigration, at least in terms of casting a wide net to catch undocumented or deportable immigrants.

Days after being inaugurated, one of Trump's first actions was to release immigration agents of specific prioritization of who to go after, giving them wide discretion to target almost any undocumented immigrant as a priority.

According to new data from Immigration and Customs Enforcement, there was a 41% increase in the number of undocumented immigrants who were arrested by the agency in 2017 compared to 2016.

But the increase was driven by the agency arresting a significantly higher rate of immigrants without a criminal background. While the share of criminals arrested was up 17%, there was an increase 10 times that -- of 171% -- in the share of non-criminals arrested.

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