As a follow on, I reviewed the 2015 Executive Summary. I didn’t find any evidence of counting the trans population. Their results are based on the relative count of those who participated in the survey. A result reads:
• One in ten (10%) respondents who were out to their immediate family reported that a family member was violent towards them because they were transgender.
”respondents” is the key word. It is a comparison within those who took the survey.
The 2,000,000 stems from data from the Williams Institute, which is a part of the UCLA School of Law. Their estimate of the trans population, released in 2016, was that we were .6% of the population. Applied to a US population of 330,000,000 results in about 2,000,000. However, a number that appears most often is about 1,400,000 which is the adult population.