Costa Rica: 10

Costa Rica gets a 10 on the environment scale because right now, they are the greenest country on the planet, and by a lot too. According to the Happy Planet Index, Costa Rica is the also the country with the happiest people due to it's environment. Life satisfaction and life expectancy in Costa Rica are ideal, while their ecological footprint is slightly below par, the other two factors average it out to make Costa Rica the greenest country on the planet. 

Luxembourg: 3

Luxembourg only gets a 3 on the environmental scale because of their ecological footprint. They have a similar life expectancy, and almost ideal life satisfaction, but their ecological footprint is the worst out of any country. Almost everyone in Luxembourg is rich, and they are very wasteful and don't care too much about their environment. They can get away with it because they are such a small country.