Table 3.

Determining the most popular sites.

Step	Description
3.1	Use the master list generated in Step 1: Developing a List of Search Queries and send a request to the Google Custom Search application programming interface (API) for every term in the master list. This API returns a list of ranked top websites as they appear on the Google search engine results.
3.2	Use the frequencies for site rankings, the Custom Search API rankings, and the relative search volume for the query to calculate the estimated proportion of site visits. For example, as shown in Table 4, the top site for the term birth control pills in the United States is the birth control pill webpage on the Planned Parenthood website [40]. The relative search volume for birth control pills in the United States in 2017 is 0.54, and the probability of someone clicking on the first site returned on the Google search engine is 0.35. Thus, the estimated proportion of site visits to Planned Parenthood is 0.19.