This information is taken from the Security Space Apache Modules Survey. Thanks Security Space!

Date	# Servers
July 2005	12,808
June 2005	11,534
May 2005	9,793
April 2005	8,751
March 2005	7,897
February 2005	6,505
January 2005	5,565
December 2004	4,995
November 2004	4,783
October 2004	4,187
September 2004	4,174
August 2004	3,863
July 2004	2,941
June 2004	2,502
May 2004	2,113
April 2004	1,792
March 2004	1,424
February 2004	1,307
January 2004	1,162
December 2003	1,009
November 2003	969
October 2003	782
September 2003	665
August 2003	522
July 2003	448
June 2003	369
May 2003	308
April 2003	250
March 2003	222
February 2003	158
January 2003	70