It comes from the 2014 Economic Report of the President, released today:
The current elevation of the unemployment rate is entirely due to long-term unemployment. In December 2013, the unemployment rate for workers unemployed 26 weeks or less fell to lower than its average in the 2001-07 period, while the unemployment rate for workers unemployed 27 weeks or more remained higher than at any time prior to the Great Recession. But the long-term unemployment rate has declined by 1.1 percentage points in the last two years, a steeper decline than the 0.5 percentage point drop in the short-term unemployment rate over that period (Figure 2-24).
For more on long-term unemployment, read my colleague Ylan Mui's smart take on the subject earlier this year.