Javascript loop doesn't work in Userscript

Question

I have a problem with userscript. I need script to load statistic for each day. But at first run day already has value 2015-10-10 (+200 days).

var today = '2015-11-26';
var year = '2015';
var month = 5;
var day = 1;
var date = '2015-05-01';
var max = 31;
var from = document.getElementById('From');
var to = document.getElementById('To');
for (var i = 0; i < 200; i++) {

 setTimeout(function () {document.getElementById("btn").click();
         from.value = date;
         to.value = date;
         if (month == 5 || month == 7 || month == 8 || month == 10) {
               max = 31;
         } else {
               max = 30;
         }
         if (day > max) {
              month++;
              day = 1;
         } else {
              day++;
         }
         if (day < 10) {
            day = '0' + day.toString();
         }
         date = year + '-' + month + '-' + day;
    }, 9000);   
}

UPDATE Not thanks to Bergi and Jamiec. Because I amn't developer, I just need to get statistic. And if you know answer you could help, guys. But I found solution:

var dates = [];
for (var i = 0; i < 214; i++) {
   if (month == 5 || month == 7 || month == 8 || month == 10) {
         max = 31;
      } else {
        max = 30;
      }
      if (day > max) {
        month++;
        day = 1;
      } else {
         day++;
       }
       if (day < 10) {
          day = '0' + day.toString();
       }
      date = year + '-' + month + '-' + day;
      dates[i] = date;
}
var j = 0;
function changeDate() {
    to.value = dates[j];
    from.value = dates[j];
    document.getElementById("btnSearch").click();  
    j++;
}

setInterval(changeDate, 4000);