This is an important point that was left out of a NYT piece discussing Janet Yellen plans for the Federal Reserve Board's interest rate policy. The piece gave Yellen's comment that it would be bad policy to wait until inflation was at 2.0 percent before more aggressively raising interest rates.
While Yellen may have been using shorthand, as she has repeatedly pointed out, the Fed views the 2.0 percent average inflation as a target. The 2.0 percent figure is not viewed as a ceiling. This means that it should be prepared to tolerate and even want periods in which inflation is somewhat above 2.0 percent. Since there will be a recession at some point, and inflation is expected to fall in a recession, to maintain a 2.0 percent average inflation rate, the rate should be somewhat above 2.0 percent before the next recession.
Given this reality, the Fed has been falling substantially short of the inflation target it set for itself.