Inconsistent Zillow Information

I am writing to get information, and voice a concern.  I see it is an issue that has come up before with this website.  People have come to use Zillow as a quide when puchasing homes, and because of this I think it is important to have the site provide the most accurate data available.  Our home is an owner-built home, still occupied by the builder.  It has been consistently, and meticulously maintained.  Despite this, this month's neighborhood data shows that absolutely every single home in our neighborhood.....EVERY HOME........increased in value except ours.  The one that has been consistently maintained and updated.  Even those that have had absolutely no improvements in 20 years increased in value.  Those that had been close to the size and value of ours increased in value.  Ours was the only one to decrease, and to decrease by a significant amount.  This is incredibly frustrating and discouraging, as it is true that people use Zillow to dispute asking prices of homes for sale.  Can any one explain to me what the situation is in my neighborhood?  I live on Wilson Lane in Paradise, CA..............Thank you