Stats are hugely mis-leading which makes it impossible to tell. A visit to your site is classed as a individual i.p address, robots and spiders from all sorts of sites will visit you and be classed as vistitors, some of these can be identified but a lot cant, yahoo spiders are the main headache as they can send a 1000+ at one time, all with unique i.ps every month/day.
Your better off comparing how many actual jobs it gets you to the phrases you target.