On reading a PhD thesis from the University of Sheffield on the phonology of West Cornwall English (excellent data collection, detailed and very meticulous methodology description) I encountered the word inputted, which set me thinking. The context was very clearly past, so to my mind input would have done the job. This made me wondering if perhaps the form overtly marked for past tense might be on the increase today?

A good tool to check this is the Google n-gram viewer, which provides written data across time that can be separated to see what is going on in British and American English. The data showed that very different processes are going on within these two varieties:

Two very different patterns. What would explain them? Any role played by prescriptivism here, with a stronger effect on American English? Further research would definitely be of interest!