From what we have noticed a general filter looks like this 100 resumes -> 30-50 short listed and phone screened -> 10 for next round of interviews -> 1-2 hires
This is for a company that looks for good programmers
Obviously this is dependent on the company and job posting. Google receives upwards of 75000 resumes a week so I'd say for highly competitive positions at moderately well known companies you're looking at roughly 25-200 applicants a week.
Perhaps a more important question is "How many qualified resumes does a recruiter receive for each open position?" With today's ease of submitting resumes, many resumes do not meet the job requirements.