The area's many colleges and universities make Boston an international center of <answer>high</answer>er education and medicine, and the city is considered to be a world leader in innovation. Boston's economic base also includes finance, professional and business services, biotechnology, information technology, and government activities. Households in the city claim the <answer>high</answer>est average rate of philanthropy in the United States; businesses and institutions rank amongst the top in the country for environmental sustainability and investment. The city has one of the <answer>high</answer>est costs of living in the United States, though it remains <answer>high</answer> on world livability rankings.
How does Boston rank on world livability?
high