In 2008, 6,450 transgender and gender nonconforming people answered a historic seventy-question survey (2008 National Transgender Discrimination Survey). This was the largest sample of transgender and gender non-conforming respondents ever compiled.
This is a critical data source, since other agencies (such as the Center for Disease Control) do not track any data on transgender and gender non-conforming people. For instance, the CDC tracks transgender women as "Men Who Have Sex With Men." We know anecdotaly and from local needs assessments that the health disparities, violence, and discrimination faced by transgender and gender non-conforming people are high. However, having statistics is a powerful way to quantify those realities and compare how different populations fare.
The main NTDS website also includes several non-English translations of certain segments. See http://endtransdiscrimination.org/report.html