In general, openness scores are based on the format and licensing of the datasets, the comprehensiveness of metadata, and what download options exist.
Dimension 2.2: Online access - Non-Proprietary format Score
This openness element measures whether data are made available in nonproprietary formats. Nonproprietary file formats are important because they allow users to access data without requiring the use of a costly, proprietary software that may prevent some users from accessing the data. Common nonproprietary formats include PDF, HTML, XLSX, DOCX, CSV, and JSON files.
Our source for this indicator is Open Data Watch.  Scores range from 0-100.  For more details, consult the ODIN technical documentation.
This openness element measures whether data are made available in nonproprietary formats. Nonproprietary file formats are important because they allow users to access data without requiring the use of a costly, proprietary software that may prevent some users from accessing the data. Common nonproprietary formats include PDF, HTML, XLSX, DOCX, CSV, and JSON files.