If you open the Terminal and run the top command at the prompt you will find information reported on Pageins () and Pageouts ().
If you are really in need of more RAM that would be indicated by how frequently the system uses VM. The Swap figure represents an estimate of the total amount of swap space required for VM if used, but does not necessarily indicate the actual size of the existing swap file. This will change as applications are opened and closed or change from active to inactive status.
The amount of available RAM for applications is the sum of Free RAM and Inactive RAM. Using Activity Monitor to read System Memory & determine how much RAM is used The computer will, however, if you start running out of available RAM for the number of concurrently running applications. The more you run the more goes into that cache. The File Cache is created by OS X as a quick store for loaded applications and processes and their support files.
