Re: It's now 2017, and your Windows PC can still be pwned by a Word file
30 years brings you well into MacOS Classic territory, which means you were very lucky for quite some time there. Just like similar OSes without any actual security (DOS/Win9x, AmigaOS, TOS, ...) there were lots of viruses going around. Though you basically had to copy software to get them, so that might explain it for you.
As to OS X malware, if we're talking targeted (nation-state/industrial espionage/whatever) malware, there's just as much "coverage", and your chances of succumbing to a targeted attack are the same (Close to 100% above a certain attacker investment).
Mass distributed stuff - well, not so much. The reason here is simple economics. The market share split for desktop systems is roughly 90/10 Win/OS X. A malware operation is much better off focusing on the 90% than the 10%. Spending what amounts to twice the work to target the extra 10% simply doesn't make sense for most operations.