"An improved rating would require stabilization of [the county's] financial position, including a track record of balanced operations and proactive financial management," Standard & Poor's said. But the county has "a lack of revenue-raising options." The AA-minus rating assigned to the pension obligation bonds reflects Marin County's "vibrant local economic base," the rating agency said. The county has "above-average wealth and income levels" and its property tax base continues to grow. The county also has a low debt burden at "a manageable 3.9% of expenditures," Standard & Poor's said. "Capital improvements have been made on a pay-as-you-go basis, and no additional debt is anticipated."