Frequencies for first 10,000 rows of pres variable in nsrd dataset :

Atmospheric |
Pressure in |
  Millibars |      Freq.     Percent        Cum.
------------+-----------------------------------
        952 |        120        1.20        1.20
        957 |        260        2.60        3.80
        967 |        260        2.60        6.40
        968 |        520        5.20       11.60
        977 |        260        2.60       14.20
        988 |        260        2.60       16.80
        990 |        260        2.60       19.40
        993 |        260        2.60       22.00
        997 |        520        5.20       27.20
       1000 |        780        7.80       35.00
       1002 |        260        2.60       37.60
       1003 |        260        2.60       40.20
       1005 |        520        5.20       45.40
       1006 |        260        2.60       48.00
       1008 |        780        7.80       55.80
       1009 |        260        2.60       58.40
       1010 |        780        7.80       66.20
       1011 |        520        5.20       71.40
       1012 |      1,560       15.60       87.00
       1013 |      1,300       13.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Jun 2016