More U.S. workers are quitting their jobs than at any time in at least two decades, according to The Wall Street Journal, creating optimism among many while also contributing to the struggles companies face trying to keep up with the economic recovery.

The wave of resignations marks a sharp turn from the height of the pandemic, when workers were scared of being furloughed or unemployed and clung to any job security they had. In April, the share of U.S. workers leaving jobs was 2.7%, according to the Labor Department, a jump from 1.6% a year earlier to the highest level since at least 2000.

The shift by workers into new jobs and careers is prompting employers to raise pay and offer promotions to hold on to talent. The desire for change by employees means many professionals are feeling confident about finding better prospects.

Turnover costs businesses money and results in disruptions but signals a healthy labor market as people gravitate to jobs more suited to their skills, interests and personal lives.

Meanwhile, office towers and central business districts aren't benefitting much from the strong economic recovery because most employees are still working from home.

Fewer than three out of 10 white-collar employees were working at the office on average in 10 major U.S. cities, including New York, Los Angeles, San Francisco and Washington, D.C., according to Kastle Systems. The nationwide security company monitors access-card swipes in more than 2,500 office buildings in cities across the country.

As of last week, an average of 31% of office workers had returned to the workspaces they occupied before the COVID-19 Pandemic, according to Kastle.

The number of employees who are back in the office has been inching up since vaccines began rolling out in the U.S. In some cases, employees have pushed back on their employers’ requests to return. In others, companies are waiting until the fall—when vaccinations will be even more widespread and schools will be in session—to more widely reopen offices.