When looking for statistics, numbers and data, ask: "Who would collect this data? Would a government agency collect this? A nonprofit? A for-profit or corporation? Would this be something reported out in a research study?"
City, state and the federal government are big collectors & publishers of data. Associations and organizations, such as KFF, are great sources of data. Corporations often publish reports, however, these can be expensive. Researchers often publish their data in journal articles. Determining which is the most likely source gives you a starting point for where to look.