WASHINGTON - The number of executions in the United States dropped 12 percent in 2010, and the number of people on death row is nearing historic lows, a report from an anti-capital punishment group said.

The Death Penalty Information Center attributed the reductions to changing attitudes toward capital punishment, but acknowledged that some of the drop may be the result of problems with the availability of chemicals used in lethal injections.

"Whether it's concerns about the high costs of the death penalty at a time when budgets are being slashed, the risks of executing the innocent, unfairness, or other reasons, the nation continued to move away from the death penalty in 2010," said Richard Dieter, the center's executive director, who wrote the report.

The group counted 46 executions in Texas, Ohio, Alabama, Virginia, Oklahoma, Mississippi, Georgia, Florida, Louisiana, Arizona, Utah, and Washington in 2010 - six fewer than in 2009, when there were 52 in 16 states.

Tennessee, South Carolina, Indiana, and Missouri did not execute anyone in 2010, but did in 2009.

The center's 2010 numbers were as of Monday. Thirty-five states, including Pennsylvania, have the death penalty.

Texas executed the largest number of people by far in 2010, but also showed the biggest drop in executions. There were 17 this year in Texas, compared with 24 in 2009. The 2010 total is the state's lowest since 2001.

The report attributed the drop in Texas to "the state's adoption of a sentence of life without parole in 2005, changes in the district attorneys in prominent jurisdictions such as Houston and Dallas, and the ongoing residue of past mistakes."

There have been 12 exonerations of death row inmates in Texas since 1978.

Nationwide, the drop may be due in part to a lack of availability of a chemical used in lethal injections, forcing more than 40 execution dates to be stayed, the report said.

It also estimated there would be 114 new inmates on death row by the year's end, a number near last year's 112, which was the fewest number of new death sentences since the penalty was reinstated in 1976.

There were 3,261 inmates on death row on Jan. 1, 2010, including 222 in Pennsylvania, compared to 3,297 at the same time in 2009.