How to track hardware resource usage statistics on OS X?
Hardware Monitor has the features you need, but only evaluation version is free.


  
  definition of artificial sensors that monitor aspects of the
  operating system, e.g. CPU load, number of processes, disk usage,
  memory usage, paging activity, network interface activity (only in
  10.4 or later)
  


Or you can make Bash script, and then import created CSV file into Google Docs or Excel to build chart.