Once you’ve decided your target market, you will need to make a decision about which channels of popular Social Media best suits the group. Based on age, income, location and education patterns have developed in usage. This great website has 2014 data of American Social Networking Platforms. Very Useful Information!
Demographics of Key Social Networking Platforms | Pew Research Center’s Internet & American Life Project.
Another American statistics infographic:
And here’s the same information in a different form for Australian usage patterns A summary
The Sensis report https://www.sensis.com.au/content/dam/sas/PDFdirectory/Yellow-Social-Media-Report-2014.pdf