Frequencies for first 10,000 rows of cstratm variable in nhamcsopd2008 dataset :

  clustered |
psu stratum |
  marker -- |
     masked |      Freq.     Percent        Cum.
------------+-----------------------------------
   2.01e+07 |      1,437       14.37       14.37
   2.02e+07 |      2,207       22.07       36.44
   2.03e+07 |        341        3.41       39.85
   2.04e+07 |      1,221       12.21       52.06
   4.01e+07 |      1,371       13.71       65.77
   4.02e+07 |      1,171       11.71       77.48
   4.03e+07 |      1,872       18.72       96.20
   4.04e+07 |        380        3.80      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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