Frequencies for first 10,000 rows of nhs variable in accident dataset :

        nhs |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      6,999       69.99       69.99
          1 |      2,983       29.83       99.82
          9 |         18        0.18      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016