Simple javascript only working in FireFox

<script type="text/javascript">
function display_year2(start_year) {
//alert(start_year);
if (start_year != "Any") {
    var i;
    for(i=document.form.year2.options.length-1;i>=0;i--)
    {
        document.form.year2.remove(i);
    }

    var x = 2009;
    while (x >= start_year) {
        var optn = document.createElement("OPTION");
        optn.text = x;
        optn.value = x;
        document.form.year2.options.add(optn);
        //alert(x);
        x--;
    }
}
else
{
    var i;
    for(i=document.form.year2.options.length-1;i>=0;i--)
    {
        document.form.year2.remove(i);
    }
    var optn = document.createElement("OPTION");
    optn.text = "Any";
    optn.value = "Any";
    document.form.year2.options.add(optn);
} // end else
} // end function
</script>

<select name="year1" id="year1">
    <option value="Any" onclick="javascript:display_year2('Any');" >Any</option>
    <option value="2009" onclick="javascript:display_year2(2009);" >2009</option>
    <option value="2008" onclick="javascript:display_year2(2008);" >2008</option>
</select>

<select name="year1" id="year1" onchange="javascript:display_year2(this.options[this.selectedIndex].value)">
    <option value="Any">Any</option>
    <option value="2009">2009</option>
    <option value="2008">2008</option>
</select>

<OPTION onclick=javascript:display_year2(2009); value=2009>

<select onchange="display_year2(this.options[this.selectedIndex].value)">
    <option value="2009">2009</option>
    ...
</select>

var i;
for(i=document.form.year2.options.length-1;i>=0;i--)
{
document.form.year2.remove(i);
}

var year2= document.getElementById('year2');
year2.options.length= 0;

var optn = document.createElement("OPTION");
optn.text = x;
optn.value = x;
document.form.year2.options.add(optn);

year2.options[year2.options.length]= new Option(x, x);