This article looks at the data a bit different... instead of looking solely at total fatalities, they examined helmet use vs no helmet use.
Centers for Disease Control and Prevention's article, "Helmet Use Among Motorcyclists Who Died in Crashes and Economic Cost Savings Associated With State Motorcycle Helmet Laws - United States, 2008-2010" in the current issue of the Morbidity and Mortality Weekly Report (MMWR)
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6123a1.htm?s_cid=mm6123a1_e%0D%0A
Centers for Disease Control and Prevention's article, "Helmet Use Among Motorcyclists Who Died in Crashes and Economic Cost Savings Associated With State Motorcycle Helmet Laws - United States, 2008-2010" in the current issue of the Morbidity and Mortality Weekly Report (MMWR)
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6123a1.htm?s_cid=mm6123a1_e%0D%0A