[Cryo]

If you run this query...

SELECT
    COUNT(b.styleid) as Users, 
    b.title 
FROM 
    (PREFIX)_user a, 
    (PREFIX)_style b 
WHERE 
    a.styleid = b.styleid 
GROUP BY 
    b.styleid ORDER BY Users DESC

It will show you how many users are using each style. This doesn't include users using the default style (styleid = 0) though, so you will need to run a separate query to figure that out...

SELECT
    COUNT(styleid) as Users
FROM 
    (PREFIX)_user a
WHERE 
    styleid = 0
GROUP BY 
    styleid

Of course you need to replace "(PREFIX)" with whatever your vB table prefix is. You could write a script or plugin to do this if so inclined, but this is the quick and dirty method of getting those numbers. It's important to note that styles you disabled that users still have selected will be counted still. For example, I used to offer a style that a very small portion of my userbase selected. I declided to stop supporting it and removed it, but after disabling it they still have it set as their style ID (even though they're viewing the default style).

Hope this helps.