Stata - selecting data to go into a panel

I am fairly new to stata and I am trying to run a cross country panel data analysis. my data comes from a variety of sources e.g. World Bank, UN etc. I have imported the data for each variable seperately into Stata but I have noticed that for each variable I have data for different years and different countries.

Is there a way to summarize for a country, the years for which I have data on a variable? I managed to find the maximum year and minimum year for each country using the command: table county (min year max year) and I ran this command for each variable e.g GDP, however for some countries I have gaps in the middle of the information. e.g data for 1960-1970, nothing for 1971-1980 but then data again for 1981-2013

As stata will just drop blank entries when I run my regression, when I merge the data I have on my variables, I need to try and find a balance between including as many countries as possible for as many years as possible. I am just not sure about the best way to go about this without writing out manually all the countries and the years for which data is provided.

Any help you can give would be great. Should this post require further clarification then please just let me know.

Many thanks :)