Custom population counter -- similar to worldometers.info

I’d like to find an odometer-style display that looks like a population counter or website hit counter. My desired odometer, however, would allow me to set the variable that governs the rate of counting. The odometer then rolls over as fast as necessary to always display the year-to-date number at the rate I have specified. Just like a population counter, but with rates that I'd control. I’d use it to display on my website the incidence of various illnesses each year. Based on the known rate of incidence of a particular illness each year (this is the variable that I would input--for example, “6,285 people in the specified population will contract XXX disease in 2011”), and the portion of the year that has passed until the present date and time, the odometer would display the year-to-date number of people who had contracted that disease-- 4,286, or 792, or 177, or whatever. The counter would continuously update while the user remains on that page. Here's an example of what I'm trying to describe (though I wouldn’t want to make dozens of them on one page like they’ve done): [login to view URL] Theirs is javascript (I have the code). Yours could be javascript or you could propose a better way.