BOSTON (AP) — Final official results from the Massachusetts primary election show fewer than 20 percent of eligible voters participated.

Secretary of State William Galvin said Thursday that about 726,000 voters went to the polls on Sept. 9, with about 566,092 casting ballots in the Democratic primary and 159,936 voting in the Republican primary.

The turnout was significantly lower than in 2006, the last time the state had an open race for governor with a contested primary and nearly 912,000 voters participated.

Official results from last week's election show Martha Coakley winning the Democratic gubernatorial nomination with 229,156 votes, to 196,594 votes for Steven Grossman and 113,988 for Don Berwick.

Charlie Baker won the GOP nomination with 116,004 votes, to 40,240 for Mark Fisher.