Here are some numbers from a press release from the Obama White House in 2014. You can take the data with a grain of salt because obviously the White House was playing up the success of the ACA, but it also gives you a feel for the basic numbers. As to your point about people signing up on the exchange because they lost coverage at work that is likely the case for some of the 8 million people who used the ACA exchanges, but it is hard to say how many.
HEALTH CARE BY THE NUMBERS
• 8 million people signed up for private insurance in the Health Insurance Marketplace. For states that have Federally-Facilitated Marketplaces, 35 percent of those who signed up are under 35 years old and 28 percent are between 18 and 34 years old, virtually the same youth percentage that signed up in Massachusetts in their first year of health reform.
• 3 million young adults gained coverage thanks to the Affordable Care Act by being able to stay on their parents plan.
• 3 million more people were enrolled in Medicaid and CHIP as of February, compared to before the Marketplaces opened. Medicaid and CHIP enrollment continues year-round.
• 5 million people are enrolled in plans that meet ACA standards outside the Marketplace, according to a CBO estimate. When insurers set premiums for next year, they are required to look at everyone who enrolled in plans that meet ACA standards, both on and off the Marketplace.
• 5.7 million people will be uninsured in 2016 because 24 States have not expanded Medicaid.
2014. The beginning of the end for Obamacare.