Wang (王) is the most common surname in the world, with a population of ~107 million (see: Wikipedia, Forebears), it could have become the 16th most populated country. This number is slightly lower than the combined population of the four most populous states (CA, TX, FL, NY), which is ~114 million.
It is difficult to have an accurate frequency of initials in Chinese characters, especially for characters used in names. Let’s just use page count in Xinhua Dictionary (12th edition) as a very crude approximation. The total page count is 664, whereas for C the page range is 40 to 79, which is ~6%. Therefore, for C. Wang, the estimated population is 6.42 million, making it the 110th most populated country in the world, or the 18th most populated state in the US.