There was an article by getbusymedia.com with some small business stats for 2011:
Small business is very important in the US.
U.S has more than 27 mi small businesses.
Small businesses with less than 100 employees represents 99% of all employers.
In most states small business accounts for about 30% of all economic activity. States with smaller populations usually have a higher % . Montana’s % is highest at 47.6%  Wyoming 43.8% and Vermont 43.4%
Small business: Annual payroll in the U. S 1.5 trillion = 30.2% (total annual was 5 trillion)
Small business: Annual revenue 7.8 trillion = 26.1 % (total annual was 29.7 trillion)
Small business: Employment 42.7 million = 35.4%Â (total employment was 120.6 million)
Small business: Establishments 6.2 million= 80.3% (total establishments 7.7 million)
Small business: Firms 5.9 million =98.2% (total firms 6.0 million
These stats are evidence a lot of our financial future depends on Main Street America. Although a lot of businesses have not survived this economy over the past few years, many small business owners keep engaging customers, and continue to work hard for growth. Small Business still remains the backbone of America.