Spain has a population of 47.21 million people in 2011, with a population density of 92 people per square kilometer. Some areas like Madrid, Guipuzcoa and Barcelona have population densities higher than the national average, while other areas such as Soria, Teruel and Zamora have lower densities. The natural growth rate in Spain has been low since 1980 due to factors like older marriage ages, more women in the workforce, and more single-parent homes. The mortality rate has also increased due to an aging population, though life expectancy is higher for women than men.