The best energy estimates are based on air and seismic wave records, compared with nuclear airbursts of comparable yield.

That is less than 200 basis points under comparable yields on 10-year Treasuries.

That is about 65 basis points, or hundredths of a percentage point, above a Treasury security with a comparable yield.

Here are some current national average yields on certificates of deposit and the comparable yields in early May.

Early known versions could destroy a two block area, with an estimated yield comparable to approximately 10 tons of TNT.

However, they may provide comparable or better yields than hypervalent iodine methods.

Thomcord is a productive variety, with a yield comparable to Thompson Seedless.

Under the Clinton proposals, she would need 8.28 percent on a taxable investment for a comparable yield.

By using sustainable agriculture methods, the amount of water usage can be dramatically reduced, while retaining comparable yields.

"It's difficult to find comparable yields in the taxable universe without taking on more credit risk," Mr. Metzold said.