As builders struggle with the rising cost of labor and building goods, the number of homes for sale has declined.

According to the National Association of Realtors, available inventory plummeted to a 3.9 month supply at the end of October. A six-month supply is generally considered to mean the market is at a healthy level.

According to Zillow, the market with the biggest drop in inventory was Seattle, which lost 28% in October, compared to 2018. Shortly following is Cincinnati, which lost 18%, and Washington, D.C., down 17%.

Also on the list was Austin, Texas, -14%; Kansas City, -16%; Las Vegas, -14%; Orlando, -10%; Phoenix, -15% and Pittsburgh, -16%.

In California, where home prices are the highest, there is also a drop in supply in all of its major markets.

According to the RE/MAX National Housing Report, in October, home sales rose by 3.9% nationwide, marking the fourth month of the past six to post a year over year increase in sales.

However, for the last six months, inventory has continued to fall.

The supply of homes for sale fell 9.1% year over year in October, the biggest decline since April 2017 and the fourth month in a row of declines, according to Redfin.

The national median home price was up over 6% compared to a year ago, the highest annual growth rate in more than two years, CNBC said.

Realtor.com also said that the average American home listing price in October climbed 4.3% year over year, reaching a high of $312,000.

Mortgage rates also dropped this year, attracting more and more buyers. As demand for little to no inventory goes up, so do the for-sale prices.