Hi gvblack,
Well I'm not sure. But beign NYU a 3 year program and the most expensive one, I'm sure most people don't have NYU as their 1st choice. So I'm sure NYU get's a lot of application withdrawls or admissions withdrawls after candidates find out they've been accepted somewhere else, maybe cheaper and shorter. Since they take 100+ students per year, it will be nice to know how many they interview to fill that many spots.
About the % of seats filled, well I ask something similar to NYU, but they won't tell me. They just said that they started their interviews in Sept or Oct (don't remember well) trough April. So probably not that many seats are filled yet.
You can always email the AdOff at NYU and ask anything. They're really friendly and usually repply back soon. Email Amy or Mara.
bye