The percentage of positive marijuana drug tests among U.S. workers rose by 11% across nearly all employee testing categories in 2019, according to an analysis released Tuesday by Quest Diagnostics Inc., Business Insurance magazine reported. In its annual drug testing index, the New Jersey-based diagnostics firm found that overall positive drug tests hit a 16-year high in 2019, accounting for surges in marijuana, cocaine and methamphetamine use. The overall positivity rate for Iowa in 2019 was 3.9%, compared with a national rate of 4.5%. In the general U.S. workforce, marijuana positivity grew from 2.8% in 2018 to 3.1% in 2019 — an overall surge of 29% since 2015, according to Quest’s data, which relies on more than 18 million urine drug test results conducted between 2015 and 2019. The analysis also found that in the first few months of 2020, drug deaths increased about 13% compared with last year, “attributable partly to social isolation and other disruptions caused by COVID-19.” To view an interactive map showing states’ positivity rates, click here.