Why are the numbers of democratic countries increasing day by day?

It is not entirely clear that the number of democratic countries is increasing day by day. There are instances like Russia, Hungary, Iraq, Turkey, and several other sovereign states that are becoming less democratic and increasingly authoritarian. However, as a general historical trend, yes, the number of democracies is increasing. The reason for this is that the economic and political success of democratic countries is quite clear around the world. Impoverished peoples under the repression of their governments note that in a democracy, at least, they have the right to complain and seek redress for their grievances.