US consumers have purchased less than 3.5 mln high-def discs: 1.4 mln HD DVDs and 2.0 mln Blu-ray discs, implying that the 1.5 mln Blu-ray owners have purchased on average 1.3 Blu-ray discs. Among the 300,000 HD DVD owners, the attach rate is much higher – 4.7 to be exact, The Diffusion group says.