This report examines start-up activity levels in the US. A steady re-acceleration of entrepreneurial activity since the downturn of 2001 has virtually restored early-stage entrepreneurship to 2000 levels. Also aspiring entrepreneurs in the United States are overwhelmingly focused on the pursuit of opportunity (versus necessity) as their principle motivation.
Link
http://www3.babson.edu/ESHIP/research-publications/upload/GEM%20UNITED%20STATES%202004%20%202005%20REPORT.pdf