Source: CDC
Information on outpatient visits to health care providers for influenza-like illness (ILI) is collected through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet). There are three datasets, one per aggregation level (region type): national, regional and state. Information about the regions can be found here: https://www.hhs.gov/about/agencies/iea/regional-offices/index.html
The format of these three datasets is the same. ILI activity for national and regional level is measured with "% WEIGHTED ILI," and "%UNWEIGHTED ILI" for state level. The distinction between these two measures is that the weighted ILI is an aggregate of the state-level data and it is weighted by state population. In the following columns, there is a breakdown per age group. "ILITOTAL" is the total number of patients with ILI symptoms. "NUM. OF PROVIDERS" is the number of healthcare providers that reported data. "TOTAL PATIENTS" is the total number of patients that visited the health care providers.