What is the test for proportionate sentences under the eighth amendment?

Under the eighth amendment, "a criminal sentence must be proportionate to the crime for which the defendant has been convicted." Solem v. Helm, 463 U.S. 277, 290 (1983). "A court's proportionality analysis under the Eighth Amendment should be guided by objective criteria, including (i) the gravity of the offense and the harshness of the penalty; (ii) the sentences imposed on other criminals in the same jurisdiction; and (iii) the sentences imposed for commission of the same crime in other jurisdictions." United States v. Kinsey, 843 F.2d 383, 392 (9th Cir.1988), cert. denied, 108 S.Ct. 2882, cert. denied, 109 S.Ct. 99 (1988).