The problem in making up a popularity chart using birth certificate data is that there is absolutely no way of knowing whether or not a particular child (or adult) is "going by" a middle name in everyday life. This sort of data just isn't available. It would be really nice to have separate lists of the most popular middle names, but to just add in the middle names with the first names would very seriously distort the true popularity of names as they are actually used, because the number of people who "go by" their middle names is small, and because there are a great many names, especially for women, which are hugely popular as middle names while being much less common as first names, such as
Ann,
Anne,
Lynn,
Marie,
Rose,
Renee, etc.