Summarize news items using view

I'm trying to create a news archive view. This seems to be almost working. If I supply an argument to the view, i.e. 200903, I get all news-items for March. However, if there is no argument supplied, I would like to get a list of all available months with the number of news-items in brackets (similar to what you get when using the argument 'Created year + month'). However, I only get a list with this month, i.e. something like "March 2009 (25)". This is the query for that case:

SELECT DATE_FORMAT(ADDTIME(STR_TO_DATE(node_data_field_datum.field_datum_value, '%Y-%m-%dT%T'), SEC_TO_TIME(7200)), '%Y-%m') AS node_data_field_datum_field_datum_value,
   COUNT(DISTINCT(node.nid)) AS num_records
 FROM node node 
 LEFT JOIN content_field_datum node_data_field_datum ON node.vid = node_data_field_datum.vid
 WHERE (node.status <> 0) AND (node.type in ('agenda'))
 GROUP BY node_data_field_datum_field_datum_value
  ORDER BY node_data_field_datum_field_datum_value ASC

When an argument is supplied, the query looks as follows:

SELECT node.nid AS nid,
   node_data_field_datum.field_datum_value AS node_data_field_datum_field_datum_value,
   node.type AS node_type,
   node.vid AS node_vid,
   term_image.tid AS term_image_tid,
   node.title AS node_title
 FROM node node 
 LEFT JOIN content_field_datum node_data_field_datum ON node.vid = node_data_field_datum.vid
 LEFT JOIN term_node term_node ON node.vid = term_node.vid
 LEFT JOIN term_image term_image ON term_node.tid = term_image.tid
 WHERE ((node.status <> 0) AND (node.type in ('agenda')))
    AND ((DATE_FORMAT(ADDTIME(STR_TO_DATE(node_data_field_datum.field_datum_value, '%Y-%m-%dT%T'), SEC_TO_TIME(7200)), '%Y-%m') <= '2009-03' AND DATE_FORMAT(ADDTIME(STR_TO_DATE(node_data_field_datum.field_datum_value, '%Y-%m-%dT%T'), SEC_TO_TIME(7200)), '%Y-%m') >= '2009-03'))
   ORDER BY node_data_field_datum_field_datum_value DESC

Am I perhaps missing something? I hope someone can help.