March 2003: MS03-007 released with only the ntdll.dll file, and there was a problem on Windows 2000 SP2 with certain versions of ntoskrnl.exe.
April 2003: MS03-013 was released with additional files to solve these problems, which also became standard for all the hotfixes.
June 2003: Windows 2000 SP4 released toward the end of June, and Windows 2000 SP2 support was supposed to end at the same time.
July 2003: MS03-026 was released just after Windows 2000 SP4.
August 2003: The Blaster worm hits, and people found out that MS03-026 could still be installed on Windows 2000 SP2. (This is not true for all of them during the period)
September 2003: MS offers "Custom Support" for Windows 2000 SP2 (originally until the end of the year), and also released MS03-039 that also works on Windows 2000 SP2 as an "exception". (https://groups.google.com/forum/#!search/custom$20support$20for$20Windows$202000$20sp2/microsoft.public.win2000.advanced_server/r-BWxTnT8Zk/Y6n5AzomkVoJ)
October 2003: MS officially extends support for Windows 2000 SP2 to June 2004 and introduced "Patch Tuesday". Trivia: https://docs.microsoft.com/en-us/security-updates/securitybulletins/2003/ms03-045 has a file date of August 2003.
April 2004: MS04-011 released with a long list of files, including even NetMeeting! (though at least RPC was a separate MS04-012) Trivia: The bug used by Sasser that was patched was reported by eEye in October 2003 (http://web.archive.org/web/20050307234702/http://www.eeye.com/html/Research/Advisories/AD20040413C.html), but not many patches for Windows 2000 was released in the meantime.
June 2004: Windows 2000 SP2 support was ended.
October 2004: MS04-032 was released with a much shorter list. For example, because of the end of support of Windows 2000 SP2, there was no ntdll.dll file.
June 2005: Windows 2000 SP3 support was ended, with six-month "Custom Support" available. From then, each patch/hotfix only patched a few files (at least the non Custom Support versions).