I'm currently doing research on the salience of did as an emphatic marker in Southern varieties of British English as illustrated in (1). I'm comparing this with the salience of did as a habitual marker especially prominent in Southwestern varieties of British English. These varieties use did as a marker of habitual aspect similar to "used to", as illustrated in (2).
(1) "Don't you think Peter ran very fast?" - "Yes, he did run very fast, indeed."
(2) "I used to go to school every day." ~ "I did go to school every day."
I'm conducting this research with the help of FRED, the Freiburg Corpus of English Dialects. (Here, have some corpus data: https://fred.ub.uni-freiburg.de/)
As I'm doing statistical research, I'd like to know if there are any surveys out there indicating a percentage of how frequent emphatic and habitual "did" are? I know the habitual use is much less common and regionally restricted, yet some numbers would be nice.
Thank you for your help!