Water condensation in my refrigerator?

We have a ten-year-old Frigidaire (Crown series). Every 4-6 days there's so much water collecting under the vegetable and fruit bins that I have to remove the bins and sponge out the water so that it doesn't leak onto our kitchen floor. This began happening last winter so I don't think it's the vegetables and fruit giving off moisture since it's not collecting within the drawers themselves. We don't open and close the refrigerator any more often than we used to either. The temperature knobs in both the freezer and refrigerator are both in the medium position. Do you have any idea what might be causing the water build-up at the bottom of the fridge?