Ubuntu – Upside-down question mark

keyboardkeyboard-layoutshortcut-keys

I'm using Ubuntu 12.04[1] with a Dvorak keyboard layout. I need to write a bunch of emails in Spanish on a daily basis and I really really need a keyboard shortcut to the inverted question mark glyph (¿), but I just can't find any. So far I've been either copying and pasting it from the character map (which is, seriously, a pain in the ass) or just not bothering with it (which I tend to avoid because it makes me look sloppy). Is there a way of defining a key combination (e.g., Ctrl + Shift + ?) that inputs this character?

[1] Yes, yes, I know it's 2014 and all that. I'm happy with 12.04 and I don't see the need to upgrade just because, so please don't tell me to.