I need some clarification on how unbalanced panel data should be organized.

For instance, suppose you have sample of total N products' prices and its factors observed during period of 3 years. Product's price is the dependent variable. This should look something like this:


Product 1 | 1998 | $100 | 22.5
Product 2 | 1998 | $175 | 22.5
Product 3 | 1998 | $199 | 22.5
Product 1 | 1999 | $100 | 19.0
Product 2 | 1999 | $180 | 19.0
....

Now, if I want to include proxy variable for quality-of-living, i.e. GDP per capita, should I put this right to the fourth column on the right for every observation in the sample like shown above?