Hey, I want to compare the development of log(gdp) of some countries in one graph. But for a better comparison I want that the first entry is 100% for every country and so on. So basically I want to generate a new index. (I don't want to compare gdp growth of the cuntries.)

The command I use is: xtline lngdp, overlay t(date) i(country)

Thankful for any replies!