The names of New York City taxi drivers

From Vizual Statistix:

Using a list of the 52,131 active medallion taxi drivers in New York City, I’ve graphed the frequencies of the 20 most common first and last names. Middle names were not considered. I did not bin alternate spellings of the same name...

The heat map below the bar graphs shows the frequency of first and last name pairings. This hints at the diversity of first or last names in some countries compared to others. For example, Singh is the most common last name, but none of the most common first names are paired with it; it is traditionally a last name in India, but due to the diversity of first names in India, none of them are in the top 20.

I would love to see comparable information for Madison, Wisconsin, but don't know how to access the database.