I had two cats, one who goes out often, one who went out once in a blue moon. The tenses tell the tale here.

And I don't mean to suggest your statistics are incorrect, just that I find it funny to have experienced the opposite. Bruce Willis lives on, and it's entirely possible his life ends outside due to any number of reasons, but he just craves the outdoors, to the point of being really annoying about it.

And it's weird, I always attribute it to my wife having found him and our other cat on the streets, they were both 2-3 years old, but Rudi took to mainly living inside (maybe she'd hang on the porch from time to time, or sat some grass), whereas Bruce yearns for the neighbors' shrubberies. He's 14ish, and hopefully we get another 14 out of him, despite him clearly going crazy.