I am looking for an online service which provides the frequency of a search phrase across all the literature in English that there is. Hopefully billions of lines of text. For example, if the phrase is "cat on a tin roof" then example output could be found 725,819 times. And then a list of documents where it is used as the outcome.
The frequency value is useful for me when writing as I could use phrases which are more popular and in many cases can see examples of popular usage. I know that such a tool exists as it was used by a former colleague who was writing a PhD thesis. But I do not recall the name of the online service.