John Mueller of Google said on Twitter "people make all kinds of links, and we ignore a lot of links, but at their core, links are not about SEO anyway." He then shared a spreadsheet of the results of the link attributes from the HTTP Archive that he grabbed a while back.
John said based on the data he reviewed, "sites use a variety of attributes."
The spreadsheet is available over here and you can see the number of times someone used different link attributes.
It looks like the frequency of using the nofollow link attribute was 42% of the time, with 31.5% of the URLs listed having them. This is followed by bookmark at 15.4$ of the time with 9.7% of URLs with them. Tag was 14.2% of the time with 7% of the URLs with them.
Here are some pie charts:
When exactly this data was captured is unknown. :)
Interesting...
Here is more of the context on why this was shared:
People make all kinds of links, and we ignore a lot of links, but at their core, links are not about SEO anyway.
— 🍌 John 🍌 (@JohnMu) July 1, 2020
FWIW I pulled the a-rel attributes from @HTTPArchive a while back, the top attributes I found are in https://t.co/zR0m2YRuSO - sites use a variety of attributes :)
Forum discussion at Twitter.