How many job candidates do companies usually interview?

I interviewed today with a nonprofit located in Honolulu. The job announcement was posted on Craigslist last week so naturally they received many, many applications. Frankly, I'm kind of amazed I even got an interview. I was just wondering if anyone knows how many candidates organizations usually interview. The hiring manager told me that "so many" people applied for the position but that doesn't give me much of an idea of how many people I'm actually competing against at the interview stage. I could be competing with 5 people or 25 people, I don't know. Also, the job was posted last Tuesday and they're supposed to make their decision this Wednesday or Thursday.