Only about 9% of US independent workers use an “on-demand economy” platform such as Freelancer.com, Uber or others, according to data released Tuesday by MBO Partners. That equates to approximately 2.7 million people. These workers tend to earn less than other independent workers, but were still satisfied with their choice to join the on-demand economy, also known as the “gig economy.”

The data comes from the MBO Partners State of Independence profiling survey, which includes 1,109 responses from independent workers. The margin of error is +/-3%. MBO Partners provides back office services for independent consultants and contractor management services for companies.

Independent workers in the on-demand economy reported lower earnings than independents not using those platforms and marketplaces. The data shows 36% of independents using on-demand platforms reported earnings of $25,000 or less compared to 22% of independent workers not using such platforms. At the other end of the spectrum, only 17% of those using on-demand platforms reported earning $75,000 or more; that compares to 28% of independents not doing so.

Even when adjusting for age and experience, those participating in the on-demand economy earn less than other independents, according to the data. Still, 79% of independent workers using on-demand services reported they are either highly satisfied or satisfied.

The survey data also found 83% of independent workers in the on-demand economy say their participation is part-time. And 68% noted they seek on-demand revenue to supplement their income.

Ranking as the most commonly used platforms were eBay, Amazon and Etsy (Craigslist was excluded), with an estimated use of 2.2 million independent workers, according to the report. Online talent marketplaces such as Freelancer.com were the second-most popular with roughly 900,000 US independent workers using them in 2014.

Sharing economy platforms such as Uber, Lyft and Airbnb ranked third with 500,000 workers using them, the report said.

Millennials represented 44% of independent workers in the on-demand economy. Gen Xers represented 32%; baby boomers were 19%; and matures, ages 68 and above, represented 5%.

Women make up 55% of independents using on-demand platforms. Only 7% of female independents use Uber and Lyft; however, 89% of female independents use Etsy and 67% use Airbnb.