Story highlights A majority of recent pardons have been granted in the final year of a president's term

Many pardons are granted in groups of a dozen or more

Most people who receive pardons average two decades since they were convicted

Washington (CNN) It was an atypical pardon from an atypical president.

When President Donald Trump granted his very first pardon to Arizonan former sheriff Joe Arpaio, he bucked process and precedent by circumventing the Department of Justice's unit dedicated to making recommendations on such requests.

But he also bucked decades of precedent for how recent pardons have nearly always been granted: a majority have come in the last year of a president's term, they usually come in groups of a dozen or more and they cancel convictions averaging more than two decades old.

Trump's pardon of Arpaio marks one of the earliest pardons in a president's term and one of the only pardons granted alone, according to a CNN analysis of Department of Justice data ranging back nearly three decades.

And we turned that data into a chart that shows how, historically, this pardon sticks out in all three major areas: numbers of years into a president's term, number of pardons issued at once and time since the conviction or sentencing.

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