In Activity Monitor, how can Swap Used be more than Page Outs?

I am trying to understand the relationship between Page Outs and Swap Used as displayed in Activity Monitor. Currently, Activity Monitor shows:

Page outs: 1.6 MB Swap used: 8.1 MB

How can there be more swap used than the amount paged out?

My understanding is this:

• Program needs access to some data. Attempts to do so, and fails, due to lack of RAM.
• OS takes control. There is a page-out operation, where physical RAM is copied to swap.
• There is a page-in operation, where the required data is copied to RAM.
• OS gives control back to program.
• Program tries again, finds its data.

OS's are getting smart about how they choose what and when to to page in/out. So the operation counts may not be the same, and the swap space may perhaps be in use without there being page outs.

Unless of course I'm backwards on what a page-in/page-out operation is. In which case your question makes perfect sense.