I Sumit my opinion in the poll that is 10-20% , no doubt that the population of the world can't be controlled but here truth is that it is not easy to teach them about the bitcoin  . But still the use and advantage of the bitcoin is going increasing day by day so more and more people are attracting toward the bitcoin , and most the countries government are looking for the legalisation of the bitcoin , so probably it may be possible that in 2020 about 10-20% people entered in The bitcoin .