Category specific monthly archives as navigation

I am using a drop down of the monthly archives as a means for navigation. However it displays a list of the archives of ALL categories. How can I make it display the archives of whatever category you are currently viewing?

eg, viewing blog archives, click dropdown and see ONLY the archives from the blog category.

<select name="archive-dropdown" onChange='document.location.href=this.options[this.selectedIndex].value;'>
<option value=""><?php echo attribute_escape(__('Select Month')); ?></option>
<?php wp_get_archives('type=monthly&format=option&show_post_count=1'); ?> </select>

That’s the code I have. Thanks