function AddYearItem(){
  var CurrDate = new Date();
  var CurrYear = CurrDate.getYear();
  for (i = CurrYear;i >= 2000;i = i-1) {
    document.JGForm.syear.options.add(new Option(i,i));
  }
}
function SelectYear(){
  document.JGForm.smonth.options.length = 1;
  for (i = 1;i <= 12;i++) {
    document.JGForm.smonth.options.add(new Option(i,i));
  }
}
function SelectMonth(){
  var syear = document.JGForm.syear.value;
  var smonth = document.JGForm.smonth.value;
  var smonth_days = new Date(syear,smonth,0).getDate();
  document.JGForm.sday.options.length = 1;
  for (i = 1;i <= smonth_days;i++){
    document.JGForm.sday.options.add(new Option(i,i));
  }
}