• mergers, consolidations and downsizing among our clients; • the level of drilling and production activity; • coordination by OPEC; • the impact of commodity prices on the expenditure levels of our clients; • financial condition of our client base and their ability to fund capital expenditures; • the physical effects of climatic change, including adverse weather or geologic/geophysical conditions; • the adoption of legal requirements or taxation relating to climate change that lower the demand for petroleum-based fuels;  • civil unrest or political uncertainty in oil producing or consuming countries; • level of consumption of oil, gas and petrochemicals by consumers; • changes in existing laws, regulations, or other governmental actions, including temporary or permanent moratoria on hydraulic  fracturing or offshore drilling; • the business opportunities (or lack thereof) that may be presented to and pursued by us; • availability of services and materials for our clients to grow their capital expenditures; • ability of our clients to deliver product to market; • availability of materials and equipment from key suppliers; and • cyber-attacks on our network that disrupt operations or result in lost or compromised critical data. The oil and gas industry has historically experienced periodic downturns, which have been characterized by diminished demand for our  oilfield services and products and downward pressure on the prices we charge. A significant downturn in the oil and gas industry could  result in a reduction in demand for oilfield services and could adversely affect our operating results. We conduct our business in over 50 countries; business outside of the United States accounted for approximately 53%, 49% and 49%  of our revenue during the years ended December 31, 2013, 2012 and 2011, respectively. Not included in the foregoing percentages  are significant levels of our revenues recorded in the U.S. that are sourced from projects on foreign oilfields. Our operations, and those  of our clients, are subject to the various laws and regulations of those respective countries as well as various risks peculiar to each  country, which may include, but are not limited to: We depend on the results of our international operations, which expose us to risks inherent in doing  business abroad. • global economic conditions; • political actions and requirements of national governments including trade restrictions, embargoes, seizure, detention, nationaliza- tion and expropriations of assets; • interpretation of tax statutes and requirements of taxing authorities worldwide, routine examination by taxing authorities and  assessment of additional taxes, penalties and/or interest;  • civil unrest; • acts of terrorism; 8