Just a bit of my own unique mental diarrhea here but I'd have thought it takes, on average, about 5 minutes to read a CV/cover letter and decide if they warrant an interview.
1000 applications x 5 mins = 5000 mins = 83.3 hours = near as damn it 12 working days with no lunch to just look through the CVs.
And there is a lot more to it than just looking through CVs!