I am having a terrible time getting Yahoo to properly index my site compared to some of the other search engines. I am fairly content rich site with a active forum. Before I go into the problem here are some basic stats:

Google shows 40,800 pages indexed.
Yahoo shows 647 pages indexed.

I get approximately 500,000 referrer hits from Google a month
I get approximately 5,000 referrer hits from Yahoo a month.

Now its understood that Google gets the most search traffic, but are these stats normal? Are most people seeing such rations such that Yahoo is providing 1% of the referrers that Google is? Something tells me probably not.

It looks like Yahoo is not indexing my entire site. Also the pages that Yahoo shows in its index are all my old link structure which i made search engine friendly a couple of months ago.

My question is does Yahoo blacklist? If so, does this look like what may have happened to my site for some reason? Does anyone have any tips that they can share with me to get past this problem?