The 2016 edition can be found here.
Alexa estimates are based on data from our global traffic panel, which is a sample of millions of Internet users using one of over 25,000 different browser extensions. In addition, we gather much of our traffic data from direct sources in the form of sites that have chosen to install the Alexa script on their site and certify their metrics. However, site owners can always choose to keep their certified metrics private.
Our global traffic rank is a measure of how a website is doing relative to all other sites on the web over the past 3 months. The rank is calculated using a proprietary methodology that combines a site’s estimated average of daily unique visitors and its estimated number of pageviews over the past 3 months. We provide a similar country-specific ranking, which is a measurement of how a website ranks in a particular country relative to other sites over the past month.