What counts?

Dorothea is stressed this week, for it is the week we have to count who comes in and out of our dear little library. We do this every week electronically, but just occasionally we have to actually sit down and do it properly (except during tea breaks, obviously - everything stops for tea and biscuits). Unless it is too busy to count - then of course we have an interesting paradox, for if we are are too busy to count then we count no-one, so we are not busy at all. And so, from morning until evening, someone sits and clicks a clicker, for a child, or for an adult. This raises some interesting existential problems - if 16 is an adult, how old is that girl with the high heels and the lippy? Do workmen count? Delivery people? Do I count a member of staff who has been out for lunch? Joanne's mum who has come to see her daughter who works in the office? Who, actually, is a person? Does the double buggy contain children or shopping - and how close can I get without seeming rude? The nice but forgetful old lady who comes in five times within half an hour - is that one visit or five?
Also, does it matter what they do here? Does someone spending six hours here count for more than someone who spends five minutes?
Statistics, make of them what you will - all I know is, I need a cup of tea. And a biscuit. With chocolate on.