Data tracking and the role that big tech companies play online has become one of the most concerning issues for parents in the U.S. — at 69% — yet is one of the least concerning for parents in the U.K. at 54%, according to data released Thursday.

The issue centers around how much time children spend online and at what age they start using the internet.

Mozilla Firefox’s survey, conducted with YouGov, aims to gain a better understanding of the dynamics. The findings, shared Thursday, explore parents’ concerns, awareness and behaviors related to online safety.

The team surveyed 3,699 parents between the ages of 25 and 55 in the United States, Canada, Germany, France, and the United Kingdom with children between the ages of 5 and 17.

The study points to additional research conducted in 2018 that found that by the time a child is 13 years old, more than 72 million pieces of personal data have been captured about them.

When it comes to big tech companies, a larger number of parents in the U.K. do not believe tech companies have their children’s best interests in mind, when compared to the U.S. and other countries surveyed.

The Mozilla survey across five countries showed that U.S. parents and children both spent the most time online. Survey takers in the U.S. reported an average of seven hours of daily internet use via web browsers, mobile apps or other devices. Their children spent an average of four hours a day online.

In France, parents spent on average of five hours online, while their children spent an average of two hours online in a typical day. As kids get older, their time online increases, too.

Parents in North America and Western Europe tend to introduce the internet to their kids between two and eight years of age. In France and Germany, kids are introduced to the internet at seven years of age and up on average.

The survey findings show that kids are introduced to the internet through mobile devices, tablets and apps, most likely through videos or school-required educational tools.

About seven in 10 parents report that they feel their child has a relatively healthy relationship with the internet. Some 80% of those in France were more inclined to think so.

Most parents speak to their children about internet safety between the ages of five and eight. Parents in the U.S., Canada and the U.K. reportedly begin these conversations earlier, while parents in France and Germany tend to introduce internet safety to children at eight years of age and up.