I am a self employed contractor, and it's not a matter of being "forced". It's not for everyone, because you have to manage your own accounting and benefits, but you can make it work just as well or better than working for someone else's company. I have a group health plan (my wife also works for our company), 401k, and my annual income is substantially greater than my last W2 job. I get a couple unsolicited contract offers every week, which is what I view as my income security. I'm pretty good at what I do, and even though contractors usually go first when layoffs happen, exceptions are often made for the people who perform well (although it's also a sign to start looking at your other options).
So while that number may include contractors, you should recognize that many contractors were not forced into it.