Countries are scored on a range of criteria: women's health indicators, their political empowerment, their participation in their country's economy and their right to education.
Even though there are great differences between top and bottom countries, such as Iceland and Sweden on the top, and Pakistan and Yemen on the bottom, no country has fully closed the gender gap. Wage inequities persist virtually everywhere.
The United States ranked 20th, behind Nicaragua and Rwanda, two among the nineteen who do a better job.
http://reports.weforum.org/global-gender-gap-report-2014/rankings/