Final answer:
The exact percentage of persons over the age of 70 who have sex with their spouses about once per week is not provided in the reference material. Sexual practices vary greatly among different age groups and are subject to continuous change and diverse personal habits.
Step-by-step explanation:
The question regarding the percentage of persons over the age of 70 who have sex with their spouses about once per week is not provided in the reference material given. However, what can be concluded from the material is that sexual practices and frequencies vary greatly among different age groups and societal categories. For instance, married couples tend to have sex more frequently than singles, with 27 percent of those in their 30s doing so at least twice a week.
Additionally, individuals over 65 continue to enjoy sex, with some research indicating a significant prevalence of HIV/AIDS in adults over sixty-five, suggesting continued sexual activity. This complex issue underscores the diverse nature of sexual habits that cannot be generalized easily and would require direct, targeted research to determine specific percentages for the age group in question.