The market for mobile health apps is getting crowded, and app developers are starting to see signs of consumer fatigue with the tools for tracking health and fitness and obtaining health-related information.

In just the past year, publishers of mobile health apps have brought to market 100,000 more apps, a 57% increase over 2015. This brings the total to 259,000 health apps globally available to consumers, according to the new study, mHealth App Developer Economics 2016 conducted by health research group Research 2 Guidance.

But consumer interest in health apps is not keeping pace with their growing numbers, suggests the report, which also includes results of a survey of 2,600 global health organizations that have developed at least one health app. The survey respondents have published 7,900 apps. The majority of the respondents, 55%, are based in Europe, and 28% are based in the U.S.

The survey attributes the app growth to three factors including an increase in the number of publishers launching multiple health apps and app publishers developing apps for Apple iOS and Android devices and even some smaller platforms such as Windows.

But while more healthcare apps come to market, the rate of growth of consumer downloads is slowing. Health apps now have a total of 3.2 billion downloads, a 7% increase from the 3.0 billion downloads in 2015, according to the study. This is a slower rate than the 35% health app download increase in 2015 and the 30% year-over-year increase from 2013 to 2014.

With so many health apps already available for download, its hard for a health app to stand out, the report finds. 53% of respondents say their health apps generated fewer than 5,000 downloads in 2015, and only 23% say their app generated between 5,000 and 50,000 downloads. That means only 24% of health apps registered more than 50,000 downloads.

Many publishers arent pleased with their overall success, although the study didnt break out many specifics. Only 43% of respondents say they have achieved their goals with their mobile app program. Mobile health apps also apparently arent big money makers62% of publishers say health apps generate less than $10,000 in annual revenue.

The apps are not making big money since most publishers have not found ways to generate significant revenue from their apps, according to Research 2 Guidance. Licensing and app development fees are the most common revenue streams, the survey says.

The study also found:

• Consumer apps are the most popular type of healthcare apps, with 56% of respondents developing apps aimed at chronically ill consumers while 33% are aimed at consumers interested in health and fitness.

• 58% of healthcare publisher use an application program interface (API), compared to 42% in 2015. Apples HealthKit is the most popular API. With the users permission, this API lets other parties feed information to Apples health app, which comes pre-loaded on iPhones. The Health apps allows consumers to look at their data from multiple health apps in one place.