For your edification, an interregnum occurs every time a pope dies.
Yes, I know. For your edification, and others who have asked you numerous times, you HAVE a seated Pope (Francis) validly elected by the College of Cardinals yet you reject him as Pope. Sedevacanists - of which you have refused to confirm or deny is your bent - reject ALL the Popes after Pius XII who died in 1958. Sixty years seems like quite a long time to be an interregnum especially since there have been six now who have worn the white zucchetto and sit on the Papal throne.
And a kitten dies every time...