3.21. The Human Development Index (HDI) is an index the United Nations uses to give a summary rating for each nation based on life expectancy at birth, educational attainment, and income. In 2006, the ten nations (in order) with the highest HDI rat ing, followed in parentheses by the percentage of seats in their parliament held by women (which is a measure of gender empowerment) were Norway 38, Iceland 33, Australia 28, Ireland 14, Sweden 45, Canada 24, Japan 11, United States 15, Switzerland 25, Netherlands 34. Find the mean and standard deviation, and interpret.