Frequencies for first 10,000 rows of shipnum variable in natl1980 dataset :

   Shipment |
     number |      Freq.     Percent        Cum.
------------+-----------------------------------
         03 |         51        0.51        0.51
         06 |      9,949       99.49      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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