Statistics from late 2003 indicate that Apple had 2.06 percent of the desktop share in the United States that had increased to 2.88 percent by Q4 2004. As of October 2006, research firms IDC and Gartner reported that Apple's market share in the U.S. had increased to about 6 percent. Figures from December 2006, showing a market share around 6 percent (IDC) and 6.1 percent (Gartner) are based on a more than 30 percent increase in unit sale from 2005 to 2006. The installed base of Mac computers is hard to determine, with numbers ranging from 5% (estimated in 2009) to 16% (estimated in 2005).