New numbers reveal how Obamacare is working to help Americans get and keep affordable health insurance.

The Census Bureau has reported that—after years of increases—the number of uninsured Americans fell from 16.3 percent to 15.7 percent. In fact, the percentage of people with private health insurance remained constant for the first time in 10 years. Experts believe this progress was driven in part by the provision in the Affordable Care Act that allows young adults to stay on their family’s health insurance plan—one of the first pieces of Obamacare to go into effect.

We’ve also learned that Obamacare is helping lower health care costs for families across the country. The Department of Health and Human Services reported that consumers saved more than $2 billion on their premiums with the help of two provisions in the health care law: more than $1 billion in rebates from insurance companies that overcharged them, and $1 billion because regulators cracked down on insurance companies who tried to increase rates without justification. The Kaiser Family Foundation released a study showing that premiums for employer-based coverage increased at historically low rates in 2011, and that employees’ share of premiums actually remained flat. All of these signs suggest that Obamacare is working to shift power away from insurance companies to the consumer and to keep premiums lower for families and businesses.

Of course, too many Americans still lack access to the security that health insurance provides, and health insurance costs remain a concern for millions. That’s why President Obama is committed to implementing the health reform law and bringing its benefits to the American people. Beginning in just over a year, middle-class families that don’t get insurance at work will be eligible for tax credits that will make coverage affordable, and the health care law will enable 30 million people to gain insurance. When the law is fully implemented, families’ premiums will be about $2,000 lower because of Obamacare.

Mitt Romney and Paul Ryan, on the other hand, have pledged to repeal Obamacare, starting on their very first day in office. They’d leave tens of millions more Americans uninsured and take us back to the days when insurance companies had unchecked power to raise premiums and price millions of families out of the health care market. We can’t afford to go back.