It depends on what Report you read. The best are by The McKinsey Global Institute, MBO Partners, The Freelancers Union in Association with Upwork, and The Staffing Industry Analysts. Of course, the US government just came out with a report last month as well.
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The challenge is, all of the survey have different assumptions and methodologies, so they come up with different numbers. The government, for example, did not include any digital talent platform work ( e.g. uber) nor did they include folks who do gigs to supplement an existing job, Steve King of Emergent Research does a great piece which reconciles this.
I too have written about this. Here is a link to my blog post, “3 Things to Know About Gig Economy Data .How to make sense about all the data out there on the Gig Economy
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