So your class had a 1% death rate due to prescription opioids. Why do you suppose it was so far out of proportion to the general population? drugabuse.gov says prescription opioids accounted for around 15,000 deaths in 2017 [1], so 12 in a single high school graduating class is either a massive unexplained spike in the data, or something you made up.
1: https://www.drugabuse.gov/drug-topics/trends-statistics/over...