Register (it is free) at this site and you will have the ability to get an incredible amount of information on existing and proposed transit stations in terms of population and median income. How do they know this stuff???
Here in Charlotte, you can select the station (example: Seventh Street Station), and find out how many residents or jobs are within .5 miles, or .25 miles. So you can compare which stations are most TOD friendly with real numbers. You can also do this for future lines in Charlotte.