According to DNR, The NPD Group estimated that men's jeans sales in the US represented 9.4% of the $52.78 billion men's wear sales in 2005. Guys! that's a whopping $4.98 billion (approx.) worth of jeans we bought. While denim is still behind the pants/slacks category, which represented 9.8% (or $5.18B), the two are not far apart.
I predict that jeans will surpass pants/slacks when the sales numbers roll in for 2006. According to the NPD numbers, pants/slacks saw a 2.4% decrease while jeans saw a 6.9% increase in sales. This trend will only continue as more professionals, young and old, opt to circulate denim into their work attire and more offices in various industries begin accepting jeans.
I had previously given my thoughts on the changing role of denim here.