Twenty-three percent of Californian voters are now registered as having "no party preference," according to figures released by the California Secretary of State on Tuesday.

It's the highest number of independent voters the state has ever registered - up 321,225 voters since the last report in April.

According to the report, 17.6 million Californians are registered to vote, with 43 percent of those registered as Democrats, 28 percent as Republicans, and 23 percent as having no party preference.

One reason for the increasing number of independent voters is due to California's new system for nominating candidates, Mark Baldassare, president of the Public Policy Institute of California, told Reuters.

The system, implemented in 2012, allows anyone to vote regardless of party, and the "top two vote-getters advance to the general election, regardless of party, making it less important for voters to declare an affiliation," said Baldassare.

"California is experiencing a dramatic increase in no party preference voters at a time when we have eliminated the partisan primaries," he said. "While the share of no party preference voters has been rising for years, the state's new voters have another reason not to affiliate with the Republican or Democratic parties."

Registered Republican voters in California are also on the decline according the figures released. In 2012, Republicans made up around 30 percent of the voting population, but as of Sept. 5, Republicans make up 28 percent of voters - a drop from nearly 5.3 million in September 2010 to slightly below 5 million in September 2014.

The number of registered Democrats increased from 7.5 million to 7.7 million, but "as a percentage of all registered voters, Democrats also dropped slightly, from 44.32 percent to 43.43 percent," said Reuters.

American Independent Party voters increased from 399,000 to 474,000, and the Peace and Freedom Party grew by about 20,000 voters, but the Libertarian Party lost about 3,000.