The number should be zero. As the nation enters 2018, the Supreme Court is considering whether to hear at least one case asking it to strike down the death penalty, once and for all, for violating the Eighth Amendment’s ban on cruel and unusual punishments.

Whether the justices take that or another case, the facts they face will be the same: The death penalty is a savage, racially biased, arbitrary and pointless punishment that becomes rarer and more geographically isolated with every year. In 2017 the total number of people sitting on death rows across America fell for the 17th straight year. In Harris County, Tex., the nation’s undisputed leader in state-sanctioned killing, the year passed without a single execution or death sentence — the first time that’s happened in more than 40 years.

Still, Texas was one of just two states — Arkansas is the other — responsible for almost half of 2017’s executions. And nearly one in three of the nation’s 39 new death sentences last year were handed down in three counties: Riverside in California, Clark in Nevada and Maricopa in Arizona.

It would be tempting to conclude from this litany, which is drawn from an annual report by the Death Penalty Information Center, that capital punishment is being reserved for the most horrific crimes committed by the most incorrigible offenders. But it would be wrong.

The death penalty is not and has never been about the severity of any given crime. Mental illness, intellectual disability, brain damage, childhood abuse or neglect, abysmal lawyers, minimal judicial review, a white victim — these factors are far more closely associated with who ends up getting executed. Of the 23 people put to death in 2017, all but three had at least one of these factors, according to the report. Eight were younger than 21 at the time of their crime.