George, the mortality rate for SARS is 15%, not 5%. The 15% is derived by dividing the number of deaths by the sum of the number cured and the number who've died. The 5% number is not correct as it takes into account the people who still have the disease.
The Flu in 1918 had a 10% mortality rate, if memory serves. 25% of the US got it, 2.5% died. We talked about this a couple weeks ago here.