When did people start putting the $ behind the numbers?

Why does it make more sense to put the $in front of the numbers?

20$
Read: twenty dollars

Makes sense

How many people do you think do it? %80?

I do this often. I write 50 or so emails a day, many of them including costs or prices on very technically challenging topics. I wrote the numbers and then add the $ sign because that is how my brain is thinking. 67,000 dollars = 67,000 $. I only do this if it is an internal email, customers never see that sh*t. Personally, I don't want to take the 3 seconds to undo it and forget my train of thought.