Fig 4. Number of cases by age at diagnosis for different routes of transmission in Chongqing and Shenzhen from their first reported cases to 2015.

Within each panel, the vertical axis represents ages from 0 to 80, while the horizontal axis corresponds to the year of the analysis from 2004 to 2015. The standardized ratio of new HIV diagnoses per 100,000 population is represented by different colors, as depicted by their color codes. The heterosexual cases in Chongqing appear to be split by two strips, which is most likely due to the low birth rates during the early 1960’s and 1980’s.