I hate it when websites do this, because it overrides the expected behavior of the browser with the author's desires. People who want each link to open in a new tab/window know about Ctrl-Click or Right-Click+Open-in-new-window. They can do it themselves if they desire. For everyone else, this is rude, annoying, and breaks the back button.
It seems like a convention that exists for sites that want to force the user into their content even when they want to leave. Unless it is a file download link - I find it incredibly rude.
I googled this for a bit, and while Google did not do a study on opening links in new tabs/windows, it seems like the University of Washington and Microsoft did: http://jeffhuang.com/Final_ParallelBrowsing_HT10.pdf
Just skimmed the abstract, which says "We find that users switch tabs at least 57.4% of the time." but looking at Table 1, it seems like 64% of people do not open search results in new tabs/windows at all, so your initial guess is about correct.
Yes. The vast majority of people do not know how to open a link in different ways. They just click the link. Unless you are making something very techy like github, design for the user that simply clicks on links. Of course, most users expect normal links to open in the current page, so don't just throw target=_blank everywhere.
I'm not so sure they have. Their 'Block all results from domain' feature doesn't register middle clicks. I'd imagine if they had been recording when people open new tabs, they also would show the Block all results link when you middle click.
It's actually quite annoying that middle click doesn't bring up the link.
Ever since I found out about the amazing middle click function, I manage to stack up probably 50-60 tabs by the end of everyday. It's hard to imagine how we managed back when there were no tabs on browsers.
