Frequencies for first 10,000 rows of smsarfip variable in natl1981 dataset :

  FIPS SMSA |
         of |
  Residence |      Freq.     Percent        Cum.
------------+-----------------------------------
       0000 |      3,977       39.77       39.77
       0120 |          1        0.01       39.78
       0400 |          1        0.01       39.79
       0450 |        419        4.19       43.98
       0520 |          1        0.01       43.99
       1000 |      2,142       21.42       65.41
       1560 |         13        0.13       65.54
       1800 |         70        0.70       66.24
       2650 |        402        4.02       70.26
       2750 |          4        0.04       70.30
       2880 |        251        2.51       72.81
       3440 |        839        8.39       81.20
       3800 |          1        0.01       81.21
       5160 |      1,023       10.23       91.44
       5240 |        566        5.66       97.10
       6025 |          1        0.01       97.11
       6080 |         13        0.13       97.24
       8600 |        275        2.75       99.99
       ZZZZ |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016