SEATTLE – In her 30 years in real estate Tere Foster has never seen waterfront inventory as low as it is now.

"Often an owner who owns a high end property - they don't need to sell...even if the market is strong,” she said Monday. “Where are they going to go? They're already economically very viable. Usually their properties are paid for."

In 2015, realtors saw international buyers and tech workers help fuel a luxury real estate market.

"We have a lot of new money coming in who wants to buy but the people who are established aren't necessarily interested in selling,” said Foster, with Team Foster at Windermere.

Another thing that helped shape this market was the economic fallout of 2008.

"We're short of product because of the crash of '08. We saw builders... well we saw an industry basically shut down for 2 to 3 years,” Foster said. "The condominium developers are very cautious because they really got hurt during the crash."

Year-end analysis from Windermere Real Estate shows 34 homes sold for $5 million or more.

Within those, 64 percent were all cash purchases. The majority of the sales, 29 of the 34, were on the Eastside and seven of them sold in ten days or less.

According to Windermere the highest price home sold in 2015 was a $13.8 million waterfront estate on Mercer Island. The highest priced single family home currently on the market in the greater Seattle area is a Meydenbauer waterfront estate listed for $32.8 million. The highest priced condominium currently on the market is a Madison Tower penthouse in Seattle listed for $9.99 million.

Foster said a new generation is fueling the need for urban dwelling.

"The millennial coming up is absolutely the most different generation we've ever, ever seen,” she said. "What's important to them in a house is quite a bit different than what we've seen in the past."

She said they’re generally looking to get out of their cars and instead ride bikes and take their dogs to work.

"[The area is] really a hot bed for these game companies and these young kids are running around with $5, $10 million,” she said. "What's important to them in a house is quite a bit different than what we've seen in the past."

"I'll tell you what that's affected is the upper, upper tier suburban market: acreage estate-type properties. Because why? They're more maintenance. You have to drive further to get to them. The more we grow here the more traffic we have."