Frequencies for first 10,000 rows of cstratm variable in nhamcsopd2011 dataset :

  Clustered |
  CSTRATM – |
    masked. |      Freq.     Percent        Cum.
------------+-----------------------------------
   2.01e+07 |      5,628       56.28       56.28
   2.02e+07 |        655        6.55       62.83
   4.01e+07 |      3,103       31.03       93.86
   4.02e+07 |        614        6.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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