A while ago, I designed pypiview, a Python package used to fetch the number of downloads for a package hosted on pypi website.
It used to work decently but according to pypi itself the values stored are not reliable and indeed sometimes it looks wierd. Besides, it looks like
the number are updated for a given release. So if you have no release for a year, you have no downloads associated.
There are now more alternatives such as those associated with bigquery. One such tool called pypinfo uses bigquery.
There is also a google interface via biquery.com available here:
SELECT COUNT(*) AS download_count FROM TABLE_DATE_RANGE( [the-psf:pypi.downloads], TIMESTAMP("2017-01-01"), TIMESTAMP("2018-01-01") ) WHERE file.project="spectrum"