Here is another statistic from the NHTSA
Table 1 - Lives Saved by Motorcycle Helmets In 2003
Motorcyclists Effectiveness Helmeted Fatalities
Operators 0.37 1805
Passengers 0.41 141
Total 0.37 1946
UnHelmeted Fatalities
Operators 1577
Passengers 138
Total 1715
The full report may be viewed at
http://www-nrd.nhtsa.dot.gov/pdf/nrd-30/NCSA/RNotes/2005/809861.pdf
