The system of election whereby each political party is given a percentage of seats that is equal to the percentage of popular votes cast in its favour is kn...

The system of election described in the question is known as proportional representation. In this system, each political party is awarded a number of seats in the legislature that is proportional to the percentage of the popular vote that it received. For example, if a party receives 30% of the popular vote, it would be awarded approximately 30% of the seats in the legislature. This system is used in many countries around the world as a way to ensure that minority parties are still represented in government and to prevent one party from dominating the political system.