Pypi stores download information in a BigQuery public dataset. It can be queried to get detail infomration about downloads. For example, to get number of downloads per version, you can run this query:
SELECT
file.version,
COUNT(*) as total_downloads,
FROM
TABLE_DATE_RANGE(
[the-psf:pypi.downloads],
TIMESTAMP("20161120"),
CURRENT_TIMESTAMP()
)
where file.project == "kubernetes"
GROUP BY
file.version
ORDER BY
total_downloads DESC
LIMIT 20
More example queries can be found here
Reference: https://mail.python.org/pipermail/distutils-sig/2016-May/028986.html