Don't know if this information has been posted or discovered in this thread yet, but after taking a while to do some research I seem to have found a reputable source and the production numbers of STi's for the years ranging from 2004 through 2007. Mind you that these numbers were for the U.S. market only, and not worldwide. However; the production numbers are low enough and with the few remaining on the road today, they are in fact and have been labeled by this source as a collector car. Discovering this gave me some good feels because the value will only increase, and if you own one within the years of 2003 to 2007 (I myself have a 2005 STi) then you're holding what's been called the best version of the STi chassis by Richard Hammond in the most recent "The Grand Tour" season opener. I'll stop boring people and post the numbers that I've found in my research. The individual production numbers for specific paint and trim are detailed in the source article.
25,813 were sold in the United States from 2004 to 2007
2004: 7,405 total