1) Determine how complete your genealogy research is. For background, read Crista Cowan's post Family History All Done? What’s Your Number? For comparison purposes, keep the list to 10 generations with you as the first person.
2) Create a table similar to Crista's second table, and fill it in however you can (you could create an Ahnentafel (Ancestor Name) list and count the number in each generation, or use some other method). Tell us how you calculated the numbers.
3) Show us your table, and calculate your "Ancestral Name Number" - what is your percentage of known names to possible names (1,023 for 10 generations).
I created an Ahnentafel report in Family Tree Maker and counted the names in each generation and came up with the following totals.
For ten generations (including me), my Ancestral Name Number (my percentage of known names to possible names) is 42%. I do think it's pretty cool that I can name all my third great grandparents.
I included names in each generation even if I didn't know the last name (or in one case a first name). For example, once you get back to the 17th or 18th century, sometimes all you get is "Susanna, wife of John Griswold" or perhaps "daughter of Benjamin Mathis, born in 1684" married Mr. Franklin.
I will also note that in many cases, I am relying on secondary, not primary, sources, but I try to evaluate them to determine if they are relatively reliable. (An online family tree is not reliable, but can be a "hint" to look for particular primary source records to confirm relationships.) One of my ongoing projects is to ensure I have accurate source citations to know where I found someone's name.
Interestingly, I have just a few more paternal ancestral names than maternal ancestral names. When I get back to the 9th and 10th generations, I find many of my dad's ancestors in Connecticut and Virginia. For my mother, I find ancestors in the 9th and 10th generations in Massachusetts and Connecticut. These states have pretty good records.
For some specifics, see a previous Saturday Night Genealogy Fun post that lists my sixteen second great-grandparents as well as noting each set of my thirty-two third great-grandparents.