No doubt you've heard plenty about the gig economy and the rise of the independent worker. Thanks to labor-market insecurity, technology, and a growing interest in controlling our own careers, more and more of us are going independent, working for ourselves on a mix of projects to make ends meet.

This has been confirmed by the fourth annual State of Independence in America workforce study from MBO Partners, though this transformation of the nation's workforce is going a bit slower than some initial boosters anticipated. The study found that there are 17.9 million "solopreneurs" in the United States, defined as those who regularly put in 15 hours or more of solo work per week.

"This is up 1.2 percent from 2013 and 12.5 percent from the base year of 2011," according to the report. Together these freelance pros generated more than $1.1 trillion in total revenue in 2014. "We expect the solopreneurs--those who consider themselves full-time independents--to grow to 24.5 million by 2019," concludes MBO.

Good old-fashioned networking still reigns supreme

But while the gig economy is growing, other big changes predicted for future workers have yet to be realized. Among them: that online gig marketplaces like Elance and oDesk will become a significant source of jobs for independent workers.

According to MBO, most freelancers still get the majority of their work from good old-fashioned networking, relying on word of mouth to send clients their way. "By far the most important source of work for solopreneur independents is network generated word-of-mouth referrals. Almost 3 out of 4 survey respondents listed word-of-mouth as their top method of getting work," the report states. Among independent workers making $100K or more per year, 84 percent said referrals were their top method of generating business.

While online marketplaces aren't making a big impact on the income streams of established freelancers, they do serve as a way to break into independent work, the report suggests. Though just 3 percent of those work more than 15 hours a week as an independent cited the likes of as their primary source of work, "they are relatively important for young and inexperienced independent workers, with 18 percent of Gen Y independents" listing them as a source of gigs and "21 percent of those who have been independent for less than one year" relying on these marketplaces as well.

MBO does expect these online tools for finding work to grow in importance, but as Steve King, a partner at Emergent Research, which designed the MBO Partners survey, told the HBR Blogs, that doesn't mean the importance of networking is dwindling. "Even when you're talking about moving to these online systems like Elance and oDesk, your reputation becomes so important, and your reputation is a function of your network," he commented. "Quite honestly, today, if you don't have access to a network that gets you introduced, you can be brilliant and get nowhere."

Whatever way they get it, they like it

Whatever way independent workers come by new gigs, most seem pretty content. More than four in five (82 percent) full-time solopreneurs told MBO that they're satisfied with their independent careers, and three in four (76 percent) plan to continue working this way.