https://www.fraserinstitute.org/sites/default/files/human-freedom-index-2017-web.pdf
"We use 2015 as the latest year in our index because it is the most recent year for which sufficient data are available."
"There is a strong correlation of 0.81 between freedom and democracy. (See Figure 11.)
The findings are not surprising, but they offer rich opportunities to empirically examine
a complex relationship in which the direction of causation or support between the two vari-
ables, if any, may strengthen or weaken over time and may be influenced by numerous other
factors, including the level of development.