Frequencies for first 10,000 rows of uca_chromo variable in natlterr2005 dataset :

      Other |
Chromosomal |
Anomalies U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          2        0.02        0.02
          2 |      4,501       45.01       45.03
          9 |      1,752       17.52       62.55
          . |      3,745       37.45      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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