Men's Body Weight Distribution

On my quest for determining how much people can lift, I developed this graph of men's body weights in pounds.  The natural log of men's weights in kilograms follows a normal distribution with a standard deviation of 0.165.  The equation I used, based on the EPA's data on the weights of American men ages 18-74, is e^(Standard_Deviations * 0.165 + 4.34) in kilograms.  The proportion of men of each weight is in percent.

Some RPG systems have rules regarding character weight.  For example, Heavy Gear and Shadowrun 4th ed. have attributes for Size or Body, respectively, based on the size of a person's body.  In real life, for the purposes of determining strength, the maximum amount of weight that a man can lift is close to 3.5 times his weight.  D&D is ridiculous for allowing halflings to have a STR of 18 at creation.