How many events take place in the US each year?  This should include
sporting events, shows/performances, concerts,
tradeshows/conferences/conventions, exhibits (eg. museum/zoo),
festivals/markets/fairs, parades, fundraisers/charity events, club
events (eg. rotary club), volunteer opportunities, community functions
(eg. church bake sale), school reunions, workshops/classes,
lectures/talks, support groups

Some of the information here may be of interest to you:

http://www.answers.google.com/answers/threadview?id=318335

Just to clarify (although it may be a stupid question): Did you want
an answer based on the exact events you listed?  If not, the question
would be impossible to answer because what counts as an event ("An
occurrence of social or personal importance" according to
Wiktionary.org) is going to vary depending on who you ask.

Personally, I think this question will be very difficult to answer
anyway because of ambiguities in many of the terms.  What *exactly*
constitutes an exhibit, or a community function?