Frequencies for first 10,000 rows of cstratm variable in nhamcsopd2007 dataset :

  clustered |
psu stratum |
  marker -- |
     masked |      Freq.     Percent        Cum.
------------+-----------------------------------
   2.01e+07 |      1,591       15.91       15.91
   2.02e+07 |      1,453       14.53       30.44
   2.03e+07 |        747        7.47       37.91
   2.04e+07 |      1,226       12.26       50.17
   4.01e+07 |      1,038       10.38       60.55
   4.02e+07 |      1,667       16.67       77.22
   4.03e+07 |      2,170       21.70       98.92
   4.04e+07 |        108        1.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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