The key is the age statistics. 6.4% of age 18-29 identify that way, double the overall total. And they broke 18-29 down by gender, showing most of those are women, with 8.3% of women age 18-29 identifying that way, almost twice as much as men in that age group. The percentages by age steadily decrease down to 1.9% for over age 65.
This is called successful recruiting. They're targetting young people for recruitment into the lifestyle and succeeding, especially with women. And the gender difference is because there is less of a stigma against homosexual women than against homosexual men. The goal of the movement is to remove the stigma completely and get these numbers up, especially among young people who can be more easily recruited. This study shows they're succeeding.
Simply an artifact of willingness to answer a telephone call.
GLBTs are oversampled simply because they answer the phone ~ and love to answer the phone!
Normal folks DON"T ANSWER unless they have an ulterior motive.