Hey @Crow T. Robot thank you and congrats on the interview! How did it go??
I was looking at the link @Warelin graciously posted and it seems in 2017 they admitted 10 and 7 students matriculated. Crow, do you think they are expanding the number of students let in? Also, my friend told me that there were only 16 interview slots on the Duke interview doodle with the request to select only one slot, which lead them to believe that there had to be fewer than 16 students interviewed.
Here's the link to the duke admissions stats: https://gradschool.duke.edu/about/statistics/all-departments-phd-admissions-and-enrollment-statistics
Good luck!!