I recently saw a poll reporting there are many people who believe smoking is harmless. After everything that has come out on this subject, including the tobacco companies admitting to conspiring to deny the reality, there are still people who think it is harmless to smoke. It occurred to me this, and other, polls could be used to find a rough, back-of-the-envelope percentage of people whom simply reject science.
What we need to do is find the percentage of people who, for a lack of a kinder phrase, fall into the tin hat category. We can do that by looking at polls on certain antiscience topics. And, to be clear, I consider all of these issues (and others) to fall in the same category. If you feel offended because some belief you hold is grouped in with others you reject, you probably need to examine your beliefs.
The percentage of people who believe smoking is harmless: 4%.
The percentage of people who believe second hand smoke is harmless: 18%
The percentage of people who believe in creationism: 42%
The percentage of people who believe the Moon landings were faked: 7%
The percentage of people who believe global warming is a hoax: 23%
I think this gives a rough estimate of the percentage of people who simply, no matter what, will reject science. This needs to be taken into account when considering issues of science - approximately 20% of the population is a lost cause when it comes to science.
NOTE: I wanted to include Holocaust deniers in this, but there has apparently been no poll on this topic since 1994 and it was very controversial when they did. That most recent poll indicated fewer than 2% of Americans denied the Holocaust.