I have panel data of more than 100 countries and 30 years. I want to assign these countries to low, lower-middle, upper-middle and high-income countries. When I download the world bank classification from the world bank website, all I get is the classified group for each country for a single year, but I want to assign the income status of each country for all the years. For example, a country is in a lower-middle-income country for the year 2020, but I want to assign this lower-middle-income status to that country for all the 30 years (i.e. from 1990-2020, that country will be assigned lower-middle-income status). Similarly, I want to do that for all the countries in my dataset. It would take a huge amount of time in excel. Is there any command in Stata which can allow me to do that?

NB: If anyone is wondering whether it would be appropriate to assign lower-middle-income status to a country which was low-income in 1995, please ignore it. Instead of income classifications, it could be regional classifications which I wanted to assign.