st: count nr of countries

[Tharshini Thangavelu <thth4658@student.su.se>]

Hi,

I have a panel dataset where I follow firms cross countries over the time
period 1998-2010. I have generated id and wants to count 
the nr of countries in my data set. How I do this? 



-- 
___________________________________________________
Tharshini Thangavelu
Forskningsassistent, Näringslivets forskningsinstitut -Ratio
Forskarbacken 19, 2tr
114 16 Stockholm
Mob 0735 53 43 90
Epost thth4658@student.su.se
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