By chance a friend emailed me asking about the small employment share in the US. I gave him the same quick response that I did in class (the US is unusually low, Japan is quite high). He found the following paper, which I’m sure you can Google. It has only partial data (e.g., nothing on self-employment, but those numbers are easy to get) but bears out my claim. However, it uses the 500 worker benchmark, which from a managerial standpoint (small = an inability to have individuals specialized across key management functions) strikes me as not “small”.
An International Comparison of Small Business Employment
John Schmitt and Nathan Lane
Center for Economic and Policy Research (Washington, DC)