CENARIO: In National City they have begun an new initiative to reduce the effects of risky sexual behavior among the 150,000 residents. 33% of the population is between 1-14 years old, 20%, 15-21 years old, 30%, 22-40 years old, and 17% older than 41. Chlamydia is the most common sexually transmitted disease with a duration that can vary from a few days to many months. Before the program began, 145, 15-21 year olds were diagnosed with chlamydia in 1996. 145 people aged 22-40 were also diagnosed with chlamydia in the same year. 16 people aged 15-40 died from chlamydia in 1996. A total of 345 people of all ages were diagnosed with chlamydia during 1996. In 1997 a sample of 3500 National City residents were recruited into a study . Each subject was asked about their current sexual behavior and each persons medical record was reviewed for diagnosis of chlamydia at the time of enrollment in 1997. 37 individuals from the sample had documentation of chlamydia of which 35% claimed to never use condoms during the same time period. Condom use in the entire sample was reported by 62% of the subjects.

What was the crude prevalence rate for chlamydia for 1996 in National City?

What was the age-specific chlamydia rate for 15-21 year olds in National City in 1996?

For 22-40 year olds?