Pete Rossi can count on one hand the number of weeks out of the year that he works more than 50 hours. But the rest of the year, his job as an actuary with the Department of Defense, provides a good living with a minimum of stress.

That partly explains why actuaries have the best job in the United States, according to a new survey by CareerCast.com that will be released Tuesday. Biomedical engineer was No. 2 and software engineer, the top job of 2012, came in at No.3. Careers that ranked the lowest included enlisted military personnel, lumberjack and newspaper reporter. (Click here to see the full ranking of all 200 jobs.)

CareerCast.com, a career website owned by Adicio Inc., ranked 200 jobs from best to worst based on five criteria: physical demands, work environment, income, stress, and hiring outlook. The firm used data from the Bureau of Labor Statistics and other government agencies to determine the rankings. As in prior years, the 200 jobs were selected for their relevance in the current labor market as well as the availability of reliable data.

Actuaries put a financial value on risk – for instance, the chances of a hurricane destroying a beachfront home or the long-term liabilities of a pension system. In a world awash with risks of the natural and manmade variety, the profession is booming, says Tony Lee, publisher of CareerCast.com. In addition, he says, "there's a severe shortage of actuaries," so wages are rising. (The median salary for actuaries in 2010 was $87,650, according to the Labor Department.)

Rossi, 31, spends his days calculating the future costs of the Pentagon's pension, health and education benefits, but says his job involves more than just crunching numbers for spreadsheets. He communicates with other government agencies and brainstorms with colleagues about financial models.