How many "current" microsoft bulletins are there?



By that I mean to say that one Microsoft bulletin ( eg. MS99-025 ) can
supersede another ( MS98-004 ) ( ref:
http://www.microsoft.com/technet/security/bulletin/ms99-025.mspx )

How can one find out?

I did look at the mssecure.xml that MBSA 1.2 uses and found that there
are (Currently) 342 'SupercededBy' tags. Is this any indicator of the
number i.e. 493 (total bulletins) - 342 (superseded) giving 151?

.