Florida taxpayers spent $57.2 million to execute the 18 men who have died in the electric chair since capital punishment was reinstated, more than six times what it would have cost to imprison them for life, The Miami Herald reported Sunday.

The newspaper calculated the cost of keeping a prisoner in jail for life, about 40 years, at $515,964. But Florida spent at least $3.17 million for each execution, largely due to the cost of years of appeals.The report concluded the death penalty is costly, slow, inefficient and failing, noting that 36 Florida death row inmates have been there more than 10 years.

"Death row is going to get bigger; the wait for execution is sure to get longer, and the cost is bound to get higher," the newspaper said.

Half of all death sentences are overturned on appeal, usually after years of expensive litigation, the paper said.

Florida has the nation's largest death row, with 296 convicted killers awaiting execution. It has executed only two men in the past two years.