Basic English proficiency in the world

Question

I am looking for data showing how all world countries compare in terms of basic English proficiency.

• In answers, the SAME METRIC should be used for all countries.
• Reasonably recent, at least after year 2000.
• The answer with most countries wins.

Pretty much any metric is welcome, for instance the number of people who passed a given test divided by population with correction for representativeness, or the proportion of the population who can handle a basic English discussion measured by UNICEF or others. The important (and difficult) thing is to have the same metric for all the world.

I am looking for basic proficiency, so at this level British/American English distinctions do not matter.

Answer 1

EF English Proficiency Index (2013)

"The EF English Proficiency Index calculates a country’s average adult English skill level using data from two different EF English tests completed by hundreds of thousands of adults every year"

...

"The EF EPI third edition was calculated using 2012 test data from about 750,000 test takers. Only countries with a minimum of 400 test takers were included in the index."

...

"We recognize that the test-taking population represented in this index is self-selected and not guaranteed to be representative of the country as a whole. Only those people either wanting to learn English or curious about their English skills will participate in one of these tests. This could skew scores lower or higher than for the general population."