Please note the report gave a statistical data. The total number of sample is not all applicants including I485 . The denominator shall be the total number of sample rather than the total number pf the applicants. If the data from the report was representative, the statement that more than one-third applicants have to wait more than 1 year for NC will be true.
Another report about long NC according to:
http://www.murthy.com/news/n_bmoreo.html
Nationwide, there are more than 25,000 cases for which name checks have been pending for more than four years
I knew several people who stuck in NC for more than 4 yrs.