- there are ~10 million people in Chicagoland
            http://en.wikipedia.org/wiki/Chicago_metropolitan_area#Metropolitan_statistical_area

- there are ~900 PCs per 1000 people in the US
            http://app.mfa.gov.sg/pr/read_content.asp?View,10464,

- there's a ~20% annual replacement rate for computers
            http://www.reuters.com/article/technologyNews/idUSL2324525420080623