Frequencies for first 10,000 rows of cstratm variable in nhamcsopd2009 dataset :

  clustered |
psu stratum |
  marker -- |
     masked |      Freq.     Percent        Cum.
------------+-----------------------------------
   2.01e+07 |      2,776       27.76       27.76
   2.02e+07 |      1,472       14.72       42.48
   2.03e+07 |        959        9.59       52.07
   2.04e+07 |      1,036       10.36       62.43
   4.01e+07 |      1,059       10.59       73.02
   4.02e+07 |        728        7.28       80.30
   4.03e+07 |      1,488       14.88       95.18
   4.04e+07 |        482        4.82      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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