I would like to know the 'rank' of how common or rare a surname is in the SSDI. Eg Smith is the most common name with 1234567 entries and Sparrell is the 12345th most common name with 123 entries. Is anyone aware of a website or program that calculates these rankings?
The site FindTheData offers something like what you are seeking by giving the frequency of surnames in the Social Security Death Index (SSDI) and their rank order. However, it holds a single dataset and does not give you any sense of change with time.
The UK site British Surnames is similar but does have two sets of data (the 1881 Census and "current") that it compares. Note that British Surnames also gives results for the USA and Australia for most names. As far as I can tell, the US data comes from FindTheData.
While many users will enjoy these sites, they may not suit Duncan because neither recognises "Sparrell" as a surname!