from PQ Media (in Mio. USD)
2002: 0.1
2003: 1.2 plus 2,340 %
2004: 6.8 plus 459 %
2005: 20.4 plus 198 %
2006: 49.8 plus 145 % (estimate)
2007: 109.5 plus 120 % (estimate)
2008: 233.9 plus 114 % (estimate)
2009: 433 plus 85 % (estimate)
2010: 757 plus 75 % (estimate)
Source: PQ Media Alternative Media Research Series Executive Summary (PDF)