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

   visit occurred in msa or non-msa |
                           location |      Freq.     Percent        Cum.
------------------------------------+-----------------------------------
msa (metropolitan statistical area) |      9,477       94.77       94.77
                            non-msa |        523        5.23      100.00
------------------------------------+-----------------------------------
                              Total |     10,000      100.00

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