CHICAGO (CBS) -- It's no secret more and more people are dying from opioid overdoses, but the number of people in Cook County killed by opioid overdoses has tripled in the last seven years.

The Cook County Medical Examiner's Office confirmed 2,000 people died of opioid overdoses last year. That breaks the previous record of 1,935 opioid overdose deaths in 2021.

In 2015, that number was just 676.

Part of the reason for the huge jump is fentanyl, a synthetic opioid, which drug dealers often use to lace with heroin, because it is highly addictive. It's 50 times more potent than heroin and 100 times more potent than morphine.

Fentanyl accounted for more than 91% of the opioid deaths in Cook County in 2022.