Frequencies for first 10,000 rows of labresref variable in namcs2012 dataset :

Share lab results |
   electronically |
  (not fax) with: |
refused to answer |      Freq.     Percent        Cum.
------------------+-----------------------------------
   Not applicable |      6,561       65.61       65.61
Box is not marked |      3,387       33.87       99.48
    Box is marked |         52        0.52      100.00
------------------+-----------------------------------
            Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016