"Common" needs to be defined better. As in, some could state that rape is common in Western Society today. (The vast numbers adding up & happening 'like clockwork') Or that in India, with their highly globalized rape statistics being reported to the Western media as if to imply rape is nonstop in India.

Was rape a problem in pre-modern times? Yes. Is it still a problem? Yes. Do we have valid statistics on what the numbers of rape were? No. We can speculate, but that is hard for several reasons.

However, we do know that slaves would be raped by their masters, pillaging warriors were not often known for treating conquered women "chivalrously", & human rights as we know them didn't even exist as a concept if you go far back enough in History.

That being said, I would advise that you set some parameters down that concentrate your question better. What time period? You mentioned Game of Thrones, were you more interested in the middle ages, focusing on Europe? Nailing those things down will give you better odds of someone answering your question that has the facts to back them.

One of the problems is that 'rape' as a concept has been redefined over time. When Middle English speakers use the word rape, it means the theft of a wife / daughter (a man's sexual "property") rather than non-consensual sex. Frankly, for a truly patriarchal society, the woman's consent isn't really material - it's about a patriarch's confidence in his offspring's progeny. This means that Mediaeval definitions of 'rape' could include kidnapping and even mere adultery, which in turn means that using contemporaneous documents to assess the scale of rape is fraught with difficulty.