I would collect information about the country's populations and the medals they received at the Olympics. I would weight the medals, so the number of gold medals x 30,000,000, the number of silver medals x 20,000,000 and the number of bronze medals x 10,000,000. I would then add these together and divide by the population. By dividing by the population, it will a give a score, which I can then use to rank the countries. I multiplied the number of medals by millions, simply so that the scores given would be reasonable integers. By dividing this by the population, it will show which countries have the most athletic populations.
The spreadsheet contains the ranked top 25 countries in the 2008 Olympics.