Mysteries: Do You Know Whodunit?

The other day I was reading Love You More by Lisa Gardner (review here) and I was thinking about what could have possibly happened in the story, who might have been the killer, who abducted the little girl, etc. It made me think about how some people claim that mysteries are too predictable, that they can always figure out "whodunit" before the story is over. I haven't found this to be true in most of the stories I've read. 

Am I the only one that rarely knows "whodunit" before the ending? 

As I read these stories, I don't always try to dissect every sentence about each character to figure out who the killer/kidnapper/etc. might be. Sometimes there are clues, and I think I know, and I'm right. Other times, I think I know and I'm completely wrong. But that's what I enjoy about these stories! I want to be wrong about who I think committed the crime! It shows that the author did a really good job of creating the mystery and throwing in twists and turns that I didn't expect! I read these type of books for entertainment, not to hone in my detective skills. Like I said, I'm often surprised by the ending and didn't see it coming. I love the twists and turns; I love not knowing until the very end what happened or who the suspect was. That's what's the most entertaining for me. I find that if I constantly try to pick things apart and figure out who it is, then I lose the story a bit and don't enjoy it as much. I'm not entirely sure why this is; maybe because I'm not paying attention to how the character is handling it and I'm more focused on my thoughts and ideas. Regardless, I like not being able to figure it out. 

I'm curious to find out if other readers are genuinely surprised by a lot of endings, or if everyone figures out "whodunit" before the end of the book and I'm in the minority.