 According to Media Research, high-definition software sales in the US were slower in the first two years than DVD software sales.16.3 million DVD software units were sold in the first two years (1997–98) compared to 8.3 million high-definition software units (2006–07).One reason given for this difference was the smaller marketplace (26.5 million HDTVs in 2007 compared to 100 million SDTVs in 1998).