According to the Fiksu App Store Competitive Index, app downloads from America’s top 200 free iPhone app providers, have declined almost 5% from March through April.

They also report that the average cost for securing a loyal customer is on the rise, mostly due to increased competition in the app marketplace. The cost went from just $1.30 in March, to $1.46 in April. That’s a more than 12% increase.

While iPhone downloads went from 4.45 million in March down to 4.23 million in April, they claim that the changes could also be due to a lack of significant events in the United States that would otherwise spur on a need for discovery and the subsequent download of apps.

Micah Adler, CEO of Fiksu comments on the trends in iPhone and other app downloads:

“April’s continued downward trajectory of app downloads was expected, as no major events sparked discovery during the month,”

“Additionally, app marketers continued to scale back their use of robotic install tactics in response to Apple’s policy on third-party marketing services.”

“However, we observed more aggressive advertising spending as marketers moved out of the first quarter lull and began to seek new opportunities to compete for rank especially in the dynamic social networking and games categories, which experienced volatility during the month,”

We will have to keep an eye on the Fiksu Index and watch what iPhone apps do for the remainder of 2012. I suspect the popularity of Android devices will be cutting into some of their business. Fiksu claims the popularity of social networking too offers increased competition, due to the availability of mobile advertising on those platforms.