Janet Yellen looked back on her year at the Federal Reserve and figured most of the boxes are checked: Accelerating economic growth, a solid employment picture and a stable financial system.

The one job left undone? Inflation.

At her final news conference as Fed chair Wednesday, Yellen said the Fed's failure to bring inflation up to the central bank's 2 percent mandate is her single disappointment.

"We have a 2 percent symmetric inflation objective. For a number of years now, inflation has been running under 2 percent, and I consider it an important priority to make sure that inflation doesn't chronically undershoot our 2 percent objective," she said.

Outside of that, Yellen said she feels comfortable with her term as chair, which will end in February when Fed Governor Jerome Powell takes over.

She leaves with the unemployment rate at 4.1 percent and trending lower, the economy shooting toward a 3 percent growth rate and banks far better capitalized than they were when the financial system melted down in 2007 and 2008.

"At the moment, the U.S. economy is performing well. The growth that we're seeing is not based on, for example, an unsustainable buildup of debt as we had in the runup to the financial crisis," Yellen said. "The global economy is doing well; we're in a synchronized expansion. This is the first time in many years that we have seen this."

Yellen said she has some concern about the values in the stock market but doesn't believe the continued surge is a major problem. And she repeated worries that she has about the continued growth in public debt, now at more than $20 trillion.

But she is heartened especially by the strong labor market.

"I feel good about the economy outlook," she said. "I feel good that the labor market is in a very much stronger place than it was eight years ago. We've created 17 million jobs, we've got a good, strong labor market and a very low unemployment rate. That's been tremendously important to the well-being of American households and workers."

Overall, Yellen said she walks away from the Fed with pride. She will not stay on after Powell is sworn in, even though her term as governor runs until 2024.

She called her time at the Fed "an immensely rewarding experience for me. I feel very positive about what we've been able to accomplish and feel tremendous loyalty to the institution. I did make the judgment that this is the right time for me to leave. But I feel that I have served in senior positions at the Fed for a long time and it's really been an honor and privilege to have the chance to do so."