I don't know if there's an "official" way to count caliber conversions, so I'll count them as 1/2.
Thus, I have:
3.5 S&Ws, including one .40 S&W/.357 SIG conversion.
4 SIG Sauers, including one 9mm/.357 SIG conversion, and one .40 S&W/.357 SIG conversion.
1 each: FN, Ruger, Harrington & Richardson.
So, exactly 1/3 of my firearms are S&Ws.