at domestic wholesalers, and in major international markets, is to maintain stocking levels under one month on average and to keep monthly levels consistent from year to year based on patterns of utilization. We have historically been able to closely monitor these customer stocking levels by purchasing information from our customers directly, or by obtaining other third-party information. We believe our data sources to be directionally reliable, but cannot verify their accuracy. Further, as we do not control this third-party data, we cannot be assured of continuing access. Unusual buying patterns and utilization are promptly investigated.

The above rebates for 2008 were higher than 2007 and reflect:

• the impact of our contracting strategies with both government and non-government entities in the U.S.; and

• a favorable adjustment recorded in 2007 based on the actual claims experienced under the Medicare Act, which went into effect in 2006,

partially offset by:

• changes in product mix, among other factors.

Performance-based 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 reimbursements to wholesalers for honoring contracted prices to third parties) reduced revenues by $1.9 billion in 2008, $1.6 billion in 2007 and $1.4 billion in 2006. Chargebacks were impacted by the launch of certain generic products in 2008, 2007 and 2006 by our Greenstone subsidiary.

Our accruals for Medicaid rebates, Medicare rebates, performance-based contract rebates and chargebacks were $1.5 billion as of December 31, 2008, and are included in Other current liabilities.

Revenues by Business Segment

We operate in the following business segments:

• Pharmaceutical

—The Pharmaceutical segment includes products that prevent and treat cardiovascular and metabolic diseases, central nervous system disorders, arthritis and pain, infectious and respiratory diseases, urogenital conditions, cancer, eye disease and endocrine disorders, among others.

• Animal Health

—The Animal Health segment includes products that prevent and treat diseases in livestock and companion animals.

 Total Revenues by Business Segment

Our pharmaceutical business is the largest in the world. Revenues from this segment contributed approximately 91% of our total revenues in 2008, 92% of our total revenues in 2007 and 93% of our total revenues in 2006. As of September 30, 2008, nine of our pharmaceutical products were number one in their respective therapeutic categories based on revenues.

We recorded direct product sales of more than $1 billion for each of nine products in 2008, each of eight products in 2007 and each of nine products in 2006. These products represented 60% of our Pharmaceutical revenues in 2008, 58% of our Pharmaceutical revenues in 2007 and 64% of our Pharmaceutical revenues in 2006.

Worldwide Pharmaceutical revenues in 2008 were $44.2 billion, a decrease of 1% compared to 2007,