Artur & Sven,

Thanks for your help! I'm using the Penn World Tables. Gretl correctly recognized it as a panel, but I hadn't set the dataset structure. When I did that, it worked...almost. Running the attached script, the first plot still has observation numbers, but the rest correctly show the year.

On the gretl web page I'm only seeing various relatively outdated version of the PWT (probably they should be updated...), apart from the fact that they don't seem to be in a formal panel structure. So how did you get or make your gretl datafile?

thanks

sven