st: assymetric start and end dates in a panel dat set

[loggyedr salvez <loggyedy@googlemail.com>]

Dear stata users,

I have a panel data set that refers to interest rates over time
accross countries.
I have observations every 4 weeks. For example

 November 1, 2009
November 29, 2009
December 27, 2009
January 31, 2010
 November 1, 2009
 November 29, 2009
  December 27, 2009
  January 31, 2010


The problem is that the  start and the end date across countries is different.

For example
               startdate-enddate
Greece   02/11/08-09/10/11
Italy        07/12/08-06/11/11
 UK          09/11/08-06/11/11


and furthermore as you can see the time interval is not the same for
all the countries (compare the time span of UK with that of Italy)
is there any solution to this problem? I want to regress interest
rates on other variables and if I do not know how to solve this
problem I might end up having wrong results. If I have to trim the
dates to obtain symmetry what would be the code for converting this
series of dates to numeric variable   ( I am referring to format time
%d, tsset identifier time and so forth)


thank you
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