How much Croatian (in its standard form) do Slovenians understand? What pair of languages would hold a similar degree of intelligibility between Slovenian and (standard) Croatian?

Slovenian and Croatian and similar languages but reportedly not as close to each other as Norwegian-Danish, Dutch-Afrikaans, Czech-Slovak or Bulgarian-Macedonian.

I understand that due to exposure to Croatian through media, immigrants, vacation...etc and that due to Croatian being grammatically easier, Slovenians understand Croatian much easier than the other way around.

But how much do Slovenians understand Croatian, from a random text, in an approximate percentage?

Also, what pair of languages would hold a similar degree of intelligibility as Slovenian and Croatian? Perhaps Italian-Spanish? Or even Portuguese-Spanish? Or Swedish-Danish? Maybe Serbian-Bulgarian?...