levels by purchasing information from our customers directly or by obtaining other third party information. Pfizer believes its data sources to be directionally reliable, but cannot verify its accuracy. Further, as Pfizer does not control this third party data, we cannot be assured of continuing access. Unusual buying patterns and utilization are promptly investigated.

We completed the harmonization of Pharmacia’s trade-inventory practices in 2003. However, such harmonization of trade-inventory practices with those of legacy Pfizer negatively impacted revenues by approximately $500 million in 2003.

Rebates under Medicaid and related state programs reduced revenues by $1.3 billion in 2005, $1.4 billion in 2004 and $800 million in 2003. Performance-based contract rebates reduced revenues by $2.3 billion in 2005, $2.2 billion in 2004 and $1.9 billion in 2003. These contracts are with managed care customers, including health maintenance organizations and pharmacy benefit managers, who receive rebates based on the achievement of contracted performance terms for products. Rebates are product- specific and, therefore, for any given year are impacted by the mix of products sold. Chargebacks (primarily discounts to U.S. federal government agencies) reduced revenues by $1.3 billion in both 2005 and 2004, and $874 million in 2003. Medicaid rebates, contract rebates and chargebacks in 2003 only include Pharmacia as of April 16, 2003. In addition, chargebacks were impacted by the launch of certain generic products in 2005 and 2004 by our Greenstone subsidiary.

Revenues

Total revenues decreased 2% to $51.3 billion in 2005 primarily due to the loss of U.S. exclusivity of certain key products, the suspension of the sales of Bextra and the uncertainty related to Celebrex. These decreases were partially offset by the solid aggregate performance in the balance of our broad portfolio of patent- protected medicines. In 2005, Lipitor, Norvasc, Zoloft and Zithromax each delivered at least $2 billion in revenues, while Celebrex, Viagra, Xalatan/Xalacom and Zyrtec each surpassed $1 billion.

Total revenues increased 17% to $52.5 billion in 2004 primarily due to the inclusion of Pharmacia results from the full year 2004

Our accruals for Medicaid rebates, contract rebates and chargebacks totaled $1.8 billion and $1.7 billion at December 31, 2005 and 2004.

Revenues by Business Segment

We operate in the following business segments:

• Human Health

—The Human Health segment, which represents our

• Animal Health

— The Animal Health segment includes treatments for diseases

 in livestock and companion animals.

products of approximately $2.8 billion in comparison to 2004. In addition, the uncertainty and patient concerns relating to selective COX-2 inhibitors and the suspension of sales of Bextra have resulted in a decline in our selective COX-2 inhibitor worldwide revenues of $2.9 billion (down 63%) in comparison to 2004. Despite these events, we were able to offset approximately $4.0 billion of those declines through our in-line products coupled with new product launches.

2005 was also impacted by increased competition and the overall market decline as branded