Frequencies for first 10,000 rows of smsarfip variable in natl1998 dataset :

       FIPS |
PMSA/MSA of |
  Residence |      Freq.     Percent        Cum.
------------+-----------------------------------
       0000 |      3,064       30.64       30.64
       0450 |        266        2.66       33.30
       0520 |          2        0.02       33.32
       0920 |         23        0.23       33.55
       1000 |      2,115       21.15       54.70
       1680 |          1        0.01       54.71
       1800 |         61        0.61       55.32
       2000 |          1        0.01       55.33
       2030 |        350        3.50       58.83
       2180 |        291        2.91       61.74
       2560 |          1        0.01       61.75
       2650 |        290        2.90       64.65
       2750 |          1        0.01       64.66
       3440 |        811        8.11       72.77
       3480 |          1        0.01       72.78
       3560 |          1        0.01       72.79
       4920 |          1        0.01       72.80
       5160 |      1,344       13.44       86.24
       5240 |        829        8.29       94.53
       5360 |          1        0.01       94.54
       6015 |          1        0.01       94.55
       6080 |          2        0.02       94.57
       7840 |          1        0.01       94.58
       8240 |          1        0.01       94.59
       8280 |          1        0.01       94.60
       8600 |        355        3.55       98.15
       8720 |          2        0.02       98.17
       9999 |        183        1.83      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015