Most developed countries have seen men's employment and activity rates fall and women's rates rise.

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The case first came to light when city and federal agencies were investigating reports of illegal prescription-drug activity at the clinic, the Women's Medical Society.

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While 15% of adult males in the U.S. are involved in early-stage business activity, 10% of women are, according to the report.

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"This study underscores the enduring importance of sex among older men and women, even among these who report infrequent sexual activity, " said Neal Cutler, NCOA's director of survey research.

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"Although the change in activity is modest, that's something that is appropriate and I think most women would be more than happy with it, " says study co-author Sheryl A. Kingsberg, Ph.

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"It's simply unacceptable that the overwhelming majority of our young women are leaving school with dangerously low levels of physical activity, " said WSFF chief executive Sue Tibbals.

BBC: Health