[R] pattern of panel waves using R

[Sebastián Daza]

Hi everyone,

Is there any command to identify the pattern of responses of a database 
with this format:

year  id
2008	1
2009	1
2008	2
2009	2
2008	3
2009	3
2008	4
2009	4
2010	4


I just need the frequency of the patterns grouped by id:

2008 2009 2010 = 80
         2009 2010 = 30
2008 2009         = 10
and so on....

Thank you in advance!

-- 
Sebastián Daza
sebastian.daza at gmail.com