These factors include high water temperatures, pollution, sedimentation, high light levels, reduced water levels and changes in salinity.

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These factors include the money fans spend on hotels, food and beverages outside of the stadium, other entertainment and non-game merchandise.

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These factors include how much funding the council receives from central government and reform of the funding arrangements for schools from 2013-14.

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These factors include your family history and your exposures to reproductive hormones (the ones your body produces as well as the ones you take in) and environmental carcinogens.

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These factors include new medicines and cheaper versions of existing drugs becoming available, Scotland's ageing population, and lifestyle issues such as obesity, smoking and alcohol misuse and associated illnesses.

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These factors include: the European sovereign-debt markets in chaos threatening the viability of the euro, the budget deadlock in the U.S. Congress, Federal Reserve Chairman Ben Bernanke implying yet more monetary ease, rating agencies threatening a downgrade on U.S. debt and Middle East turmoil.

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