ie和firefox中getyear()不同

      <select name="showyear" id="showyear">
         <script>
    var date=new Date();
   var month=date.getMonth()+1;
   var year;
   var agt=navigator.userAgent.toLowerCase();
	if(agt.indexOf("msie")>=0){
	year=date.getYear();
	}else if(agt.indexOf("firefox")>=0){
	year=date.getYear()+1900;
	}
	for(var i=(year-5);i<(year+6);i++){
		if(i==year){
		document.write("<option selected='selected' value='"+i+"'>"+i+"</option>");
		}else{
		document.write("<option value='"+i+"'>"+i+"</option>");
		}
	}
   
   </script>
      </select>