The National Retail Federation's data is in. The verdict: Holiday sales are on the decline, thanks to the economy.

The NRF defines "retail industry sales" as a total sum of traditional retail sales from discount stores, department stores, grocers and specialty stores. It does not include online shopping.

Since the NRF began tracking holiday shopping data in 1992, 2008 was the first year that holidays sales were noticeably decreasing. There has been a 3.4% decrease in holiday retail sales from 2007 to 2008, making researchers question what will happen in the 2009 holiday season.

2008 earned nearly 442 billion dollars in holiday retail sales, almost 18.5% of the entire year's industry sales. It might seem like a lot, but, realistically, it's a 15 billion dollar drop in holiday sales when compared to the 2007 season.

1999-2007 showed a rise in holiday retail sales, before declining last year:

• 1999: $344.20 billion
• 2000: $352.16 billion
• 2001: $364.12 billion
• 2002: $368.77 billion
• 2003: $387.16 billion
• 2004: $410.33 billion
• 2005: $433.46 billion
• 2006: $448.03 billion
• 2007: $457.75 billion
• 2008: $441.97 billion