A recent survey found that 57% of Americans have not even executed a basic will, including 22% of people over the age of 65. Interestingly, about one-third (32%) said they would rather go without sex for a month or would prefer having a root canal over creating or updating a will.
Here's a link to the article describing the survey. One important caveat: the article refers readers to websites that specialize in "do it yourself" estate planning. Creating a proper estate plan comprises far more than just executing a will or other boilerplate document, so if you choose to do so without professional advice, proceed at your own peril.