There were 149 known exonerations in 2015, where the exonerated defendants served on average more than 14 years in prison, said the report from the National Registry of Exonerations. That topped the previous recorded high of 139 in 2014.

The issue has gained attention because of the hit Netflix documentary series “Making a Murderer,” which suggests authorities planted evidence against two Wisconsin men convicted of murder, an allegation rejected by local law enforcement.

“There is a coming to terms that this is a regular problem, not just something that happens once in a while and unpredictably,” said Samuel Gross, a law professor at the University of Michigan and editor of the registry.

“But progress so far is a drop in the bucket.”