Hello, I have a dataset of european regions for each year, but there are multiple entry of each region for each corresponding year. How do I summarise for each region according to each year. Keeping it in mind the xt function doesnot work since there are repeated time values within the panel.

The data looks as of below

region year value
1 2007 0.8
1 2007 0.9
1 2007 0.7
1 2008 0.6
1 2008 0.888
2 2007 0.4
2 2007 0.9

I need to calculate yearly total for each region.


Thank you.