The wearable activity tracking device market is one of the fastest growing tech categories, according to a report from the Consumer Technology Association. 

Some 20 percent of US households now own an activity tracking wearable device, which is nearly double the households that owned these devices last year. CTA also said that another 15 percent of households planned to purchase an activity tracking wearable in the next year. The CTA, which puts on the big consumer electronics show, CES, in Las Vegas every January, conducted a telephone survey of 2,015 adults in the US for its report.

“Wireless, portable, connected devices are driving tech adoption,” CTA President and CEO Gary Shapiro said in a statement. “Highly sophisticated tech devices such as wearable health trackers and Bluetooth-enabled headphones are now available in a wide array of styles and price points, making them more accessible for households across the country – improving our productivity, entertainment experiences and wellness, across generations.”

Recently, a different report from Nielsen found that in the US, smartphones are the most used technology platform. Nielsen reported that smartphone penetration has reached 82 percent in the US, which is a good sign for digital health-focused companies aiming to reach a large portion of the country.

“Smartphone penetration is nearly as high as TV set and radio ownership, and consumers carry their phones everywhere,” Nielsen SVP of Audience Insights Glenn Enoch said in a statement. “High penetration plus portability and customized functionality have made them a staple of consumers’ media diet. Smartphones provide advertisers and marketers with the opportunity to reach consumers with information throughout the day.”

Two other smartphone-related reports came out recently, from Juniper Research and Strategy Analytics that found smartphones shipments have declined in the last year.

Juniper Research estimated that smartphone shipments reached 320 million in Q1 2016, which is a year over year decline of 6 percent. While Samsung and Huawei saw increases in revenue and shipments, a number of other big name smartphone companies, including Apple, Xiaomi, Lenovo, Microsoft, and Sony, saw drops.

Meanwhile, Strategy Analytics reported that global smartphone shipments fell 3 percent annually from 334.6 million shipments in Q1 2015 to 335 million units in Q1 2016. Strategy Analytics added that this is the first time since the smartphone market first began in 1996 that global shipments have shrunk on an annualized basis.