By David Wetzel New York (Knewz) — The number of people in the United States workforce who tested positive for drugs in 2021 was at the highest level in two decades, according to a new study. According to data released by Quest Diagnostics on March 30, the positivity rate among the combined workforce was up 4.6 percent last year compared to 4.4 percent in 2020. That 2021 total matches the rate from 2001 after years of decline. The number was up 31.4 percent from an all-time low from 2010-2012, when 3.5 percent of the workforce tested positive, the study found. The combined workforce includes g…