Help me with "Archive drop down" in menu.

I want to add an archive drop down in the menu but can’t seem to figure it out.
I want it to work like my categories drop down.

This is the code in functions.php:

function custom_menu(){
	echo '<ul id="top-menu">';
	$data = wp_list_categories('show_count=1&echo=0&title_li=<a href="#">Categories</a>');
	$data = preg_replace('/\<\/a\> \((.*)\)/',' <span>$1</span></a>',$data);
	echo $data;
	wp_list_pages('title_li=&');
	echo '</ul>';
}

So basically I want a “button” which sais “Archive”, and when you hover your mouse over it, a drop down menu appears with all months.