Frequencies for first 10,000 rows of musculo variable in natl1997 dataset :

      Other |
musculoskel |
etal/integu |
     mental |
  anomalies |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          5        0.05        0.05
          2 |      9,983       99.83       99.88
          9 |         12        0.12      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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