Query: Voters in the city approve which kind of amendment?
Context: Left-wing politics have been particularly strong in municipal government since the 1960s. Voters approved charter amendments that have lessened the penalties for possession of marijuana (1974), and that aim to protect access to abortion in the city should it ever become illegal in the State of Michigan (1990). In 1974, Kathy Kozachenko's victory in an Ann Arbor city-council race made her the country's first openly homosexual candidate to win public office.