As the amount of data that marketers rely on continues to grow, many are finding that they need outside help managing it.

According to a Q4 2017 survey of US marketers by Adestra and Ascend2, 43% of respondents reported that they outsource their data-driven marketing strategies. While the majority of the respondents use a combination of outsourced and in-house resources, just 5% rely strictly on in-house resources to manage their data.

Data-driven marketing isn’t exactly new. But many marketers are looking for data management assistance that comes from outside their companies because the landscape is changing rapidly, according to Stephani Estes, senior vice president director of media strategy at ad agency Cramer-Krasselt.

For example, in previous years marketers didn’t need to worry much about the EU’s General Data Protection Regulation (GDPR), which states that people’s data can only be used if they give a company explicit permission.

But now that compliance of GDPR becomes enforceable in May, marketers are having to familiarize themselves with new types of tech vendors like customer data platforms, which exclusively focus on managing and storing first-party data. These quickly evolving industry changes increase the need for data expertise, which marketing firms don’t always have a steady supply of.

The need for outsourced help with data is also reflected in the lack of advertisers that completely bring their programmatic ad buying in-house. In an August 2017 survey of brand advertisers worldwide by Infectious Media, 84% of respondents said they wanted more control over their programmatic efforts, but only 1.4% had taken steps to bring their programmatic buying in-house.

“We often hear from clients that they recognize the importance of a data-driven marketing strategy,” Estes said. “But putting one into practice can be a real challenge.”