In a nutshell, my question is: what is the typical growth of
Application Service Providers (ASP's)? Growth is defined as increase
in profits and/or number of customers from year to year to year.

I am writing a business plan for my company. The company's business
model is that of an Application Service Provider (ASP). We provide a
web-based service for a monthly fee.

I would like to prepare sales forecast figures based on industry
figures for the typical growth of ASP's.Some random examples of ASP's
include:
http://www.eznettools.com/  
http://smallbusiness.yahoo.com/merchant/index2.php?rn=8918685
http://www.maestrocms.com/