- Country
a character vector, name of each country.
- AO
a numeric vector, cars per person.
- POP
a numeric vector, population of country in millions.
- DEN
a numeric vector, population density.
- GDP
a numeric vector, per capita income in U.S. dollars.
- PR
a numeric vector, gasoline price in U.S. cents per liter.
- CON
a numeric vector, Tonnes of gasoline consumed per car per year.
- TR
a numeric vector, thousands of passenger-kilometers per person of bus and rail use.