Approximately 6 percent of all U.S. adults are involved in starting businesses. Why aren't more (or less) people involved in starting a business?

Approximately 6 percent of all U.S. adults are involved in starting businesses. 

Why aren't more (or less) people involved in starting a business?

Why are men more likely to start businesses than women?

What factors might account for this difference?

And who is more likely to start a business: someone who is unemployed, working full time, or working part time?