What was the question for this implicit rationale, and corresponding answer?
This is the relevant information: In 2010, a death row inmate waited an average of 178 months (roughly 15 years) between sentencing and execution.
The answer: an average of 178 months ( roughly 15 years )
The question: In the United States, prisoners may wait many years before execution can be carried out due to the complex and time-consuming appeals procedures mandated in the jurisdiction. The time between sentencing and execution has increased relatively steadily between 1977 and 2010, including a 22 % jump between 1989 and 1990 and a similar jump between 2008 and 2009. In 2010, a death row inmate waited an average of 178 months (roughly 15 years) between sentencing and execution. Nearly a quarter of inmates on death row in the U.S. die of natural causes while awaiting execution.

Answer this question: how long is an inmate on death row?