Frequencies for first 10,000 rows of firstyear variable in nda2segments dataset :

 First Year |
NDC Appears |
   in State |
       Drug |
Utilization |
       Data |      Freq.     Percent        Cum.
------------+-----------------------------------
       1991 |      6,345       63.45       63.45
       1992 |        919        9.19       72.64
       1993 |        280        2.80       75.44
       1994 |        128        1.28       76.72
       1995 |        137        1.37       78.09
       1996 |        165        1.65       79.74
       1997 |        121        1.21       80.95
       1998 |        133        1.33       82.28
       1999 |        116        1.16       83.44
       2000 |        102        1.02       84.46
       2001 |        105        1.05       85.51
       2002 |        130        1.30       86.81
       2003 |         81        0.81       87.62
       2004 |         42        0.42       88.04
       2005 |         59        0.59       88.63
       2006 |         77        0.77       89.40
       2007 |         76        0.76       90.16
       2008 |        140        1.40       91.56
       2009 |         70        0.70       92.26
       2010 |        123        1.23       93.49
       2011 |         92        0.92       94.41
       2012 |        154        1.54       95.95
       2013 |        138        1.38       97.33
       2014 |        103        1.03       98.36
       2015 |         79        0.79       99.15
       2016 |         44        0.44       99.59
       2017 |         41        0.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Feb 2018