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

  clustered |
psu stratum |
     marker |
   (masked) |      Freq.     Percent        Cum.
------------+-----------------------------------
   2.01e+07 |      2,443       24.43       24.43
   2.02e+07 |      1,868       18.68       43.11
   2.03e+07 |        923        9.23       52.34
   2.04e+07 |        840        8.40       60.74
   4.01e+07 |      1,184       11.84       72.58
   4.02e+07 |        906        9.06       81.64
   4.03e+07 |      1,225       12.25       93.89
   4.04e+07 |        611        6.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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