sitemap URLs vs indexed URLs in Google for a new site

The number of indexed URL's shown in my Google sitemaps page peaked at 26,000 out of 65,000 URLs in my sitemaps last week. Over the last few days the number of indexed URLs has started to fall slowly and is now down at 24,000. This makes me slightly worried. I hope that it will start growing again soon or something is not working as expected.

A couple of months after the launch of the new vBulletin+vbSEO version of my forum the number of indexed URLs has now stopped increasing. The number of indexed URLs peaked at about 25,000 out of 65,000 URLs in the sitemaps. Over the last few weeks the number of indexed URLs have started to slowly decrease and are now down at 18,000 indexed URLs. The forum I am refering to can be found here:

CFD Online Discussion Forums

* sigh * something is not working that well and for some reason Google doesn't want to index more than 25% of the URLs in my sitemap. I am not sure if it is due to vbSEO and how the forum is set up or if it is something else that causes this.

what are you inlcuding in your sitemap?

I just thought I'd post a followup to my old question to inform others about what has happened. Slowly, very slowly, the number of indexed URLs has increased. The increases seem to happen in steps, and then for a long time the number of indexed URLs slowly falls, until a month or so has gone and it takes another big step up. I assume that is due to Googles way of indexing.

Now, more than hald a year ago after we launched our new vBulletin+vbSEO version of our forum, we are now up at more than 60,000 indexed URLs out of about 70,000 in our sitemaps. This is starting to approach the figures given by briansol. I guess I was just too optimistic about how long it would take for Google to index our sitemap URLs.