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

       Year |      Freq.     Percent        Cum.
------------+-----------------------------------
       1991 |        507        5.07        5.07
       1992 |        507        5.07       10.14
       1993 |        507        5.07       15.21
       1994 |        507        5.07       20.28
       1995 |        507        5.07       25.35
       1996 |        507        5.07       30.42
       1997 |        507        5.07       35.49
       1998 |        507        5.07       40.56
       1999 |        507        5.07       45.63
       2000 |        497        4.97       50.60
       2001 |        494        4.94       55.54
       2002 |        494        4.94       60.48
       2003 |        494        4.94       65.42
       2004 |        494        4.94       70.36
       2005 |        494        4.94       75.30
       2006 |        494        4.94       80.24
       2007 |        494        4.94       85.18
       2008 |        494        4.94       90.12
       2009 |        494        4.94       95.06
       2010 |        494        4.94      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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