Frequencies for first 10,000 rows of examwi2 variable in nhamcsopd2004 dataset :

       exam |
write-in #2 |
  - 4 digit |      Freq.     Percent        Cum.
------------+-----------------------------------
       0000 |      9,561       95.61       95.61
       8913 |          4        0.04       95.65
       8926 |         65        0.65       96.30
       8931 |          1        0.01       96.31
       8934 |          5        0.05       96.36
       8936 |         24        0.24       96.60
       8939 |        211        2.11       98.71
       897- |          1        0.01       98.72
       9509 |        127        1.27       99.99
       9541 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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