State populations

Suppose you come across a table containing 3 fields:

• country name (country_name)
• state name (state_name)
• total population (total_population) #total population for a given state

Using this information, write a function in SQL that returns the following:

• state_name | total_population | percent_of_country_population

Note the last field, percent_of_country_population, can be calculated by dividing each individual state's population by the total population of its associated country in the table.