It’s a trend that has increasingly concerned local economists: Hawaii has an ever-growing number of visitors, but income per visitor is declining. So why the shift of needing more and more people — and the negative side effects they bring — just to maintain the same level of economic benefits?

The Hawaii Tourism Authority recently released data which might explain the trend. While the growth of vacation rental houses, thanks to sites like Airbnb, has made it easier than ever for people to rent vacation houses, the numbers show that people who stay in the properties tend to spend much less than their counterparts staying in hotels.

And it’s not just for losing accommodations that people spend less when they stay in a vacation home. Aside from spending a little more for transportation, the data show the rental house crowd spend less across the board: on shopping, entertainment and food and beverage.