Amtrak’s Downeaster set another ridership record, completing its fiscal year with 528,292 passengers, the highest in its 10-year history, officials said Tuesday. Ridership figures for the fiscal year that ended June 30 represent the seventh consecutive year of growth, the Northern New England Passenger Rail Authority said. Ridership grew 4 percent in fiscal 2012, and ticket revenue grew by 4.5 percent, the authority said. The trend tracks with growing ridership overall for Amtrak, which has set records in eight of the last nine years and topped 30 million passengers for the first time last year. The Northern New England Passenger Rail Authority, which operates the Downeaster, said it cannot pinpoint any single factor for the ridership increase. But it said surveys indicate there are more repeat customers.