For most Americans, the enrollment period to sign up for insurance plans under the Affordable Care Act ends tomorrow.John Yang has a look at the numbers so far.William, the latest government figures show that, as of last Saturday, more than 4.1 million people had signed up for ACA coverage.That's down nearly 12 percent from last year, and the number of new enrollments is down almost 20 percent,this despite stable premiums and more plans available.Now, millions more are expected to sign up or be reenrolled by tomorrow's deadline.To discuss what's going on, we're joined by Julie Rovner, chief Washington correspondent for Kaiser Health News.Julie, thanks and welcome. Why is enrollment down from last year?Well, there are a lot of reasons. A big one, of course,is that Congress last year repealed what's called the mandate penalty, so if you don't have health insurance,you will no longer have to pay a tax penalty for not having it, although a lot of people actually don't even know that.The economy is better. More people have jobs. They don't need their own health insurance. There are some smaller things.In Virginia, they're expanding Medicaid, so you have got tens of thousands,more than 100,000 people who were getting ACA coverage who will now be able to get Medicaid.And the Trump administration allowed these short-term plans, these alternative kinds of plans, that might be cheaper if you're healthy.And there are some number of people who are probably going to sign up for those plans instead,so there are a lot of things that are contributing to this.So, even though enrollment is down, that doesn't mean necessarily that people, that coverage is down?We don't know yet. We won't find that out for several more months.