The Death of the Death Penalty

The New York Times is reporting about a study that finds fewer and fewer death sentences are being handed out in each of the past four years. From a 1990s average of almost 300 death sentences imposed every year, the number has dropped to 174 per year. As activits fight to get rid of the death penalty through legislative means or the courts, one wonders if the jury system may simply weed out the punishment in a more practical way. Also, if it's true that the death penalty has overwhelming public support, how come the "public" sitting on juries are imposing it less often?