Frequencies for first 10,000 rows of bioprov variable in namcs2015 dataset :

     Biopsy |
   provided |      Freq.     Percent        Cum.
------------+-----------------------------------
         -9 |         26        0.26        0.26
         -7 |      9,706       97.06       97.32
          1 |        245        2.45       99.77
          2 |         23        0.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 25 Oct 2017