Every parent knows that once their kids hit a certain age and teeth start falling out, it's time to pay up. But many parents these days wonder if there is a "right" amount of money to leave under a child's pillow from the tooth fairy? Well, the answer might surprise you. The Original Tooth Fairy Poll conducted by Delta Dental recently revealed that a lost tooth now nets an average of $4.13, and that's down from last year's $4.66. This marked a departure from the poll's steady correlation with the stock markets.“Most years, Ms. Fairy leaves a bit more under the pillow when the S&P 500 is up,” the website states. “However, her cold cash payouts couldn’t keep up with the hot stock markets this year.” If four bucks sounds like a big jump from your childhood, you're not wrong. Another survey released by personal finance company LendEDU last week told a similar story. Members of Generation Z receive an average of $3.25 per tooth, while millennials earned $2.13, Gen Xers got $1.39, and Baby Boomers scored a mere 69 cents. The difference doesn't sound so big when adjusting for inflation, however. Baby Boomers actually got the best deal, with $5.77 in today's money, and Gen Xers getting $5.54, and millennials actually receiving the least with $3.72. Don't worry about counting out exactly 13 quarters for your kid's next molar though. Approximately one third of parents still leave a dollar, by far the most popular amount in a 2015 Visa survey. That doesn't stop other families from handing out $5, $10, or even $20 for incisors, Moneyish reports. Whatever number you land on, remember this: kids lose a whopping 20 teeth, so big payouts add up quickly. And if you're wondering when this strange tradition developed in the first place, the origin of the tooth fairy actually only dates back to the early 20th-century. The folklore may stem from the mouse mascot (La Petite Souris or Ratóncito Pérez) that performs the gift-for-tooth duties in many other countries around the world. No matter who's doing the job (and let's face it — it's the parents!), the legend has stuck as a rite of passage that soothes kids, encourages oral hygiene and teaches a financial lesson all at the same time.