function calcDays(currentDate) {
// create a date object for January 1 of the next year
   newYear = new Date("January 1, 2007");  // insert a temporary date for January 1
   nextYear = currentDate.getFullYear()+1; // the year value of the next year
   newYear.setFullYear(nextYear);          // change newYear to the next year

// calculate the difference between currentDate and December 15
   days = (newYear - currentDate)/(1000*60*60*24); // convert milliseconds to days
   return days;
}