;Legend
Senate • Gaps refer to instances when the legislature was unicameral.
House of Representatives • Gaps from 1946 to 1971 refer to instances when there was no lower house election for it was a midterm election (senators have 6-year terms with
staggered elections every two years, while representatives have 4-year terms). Starting in 1995, a midterm election includes both upper and lower house elections (senators have 6-year terms with staggered elections every three years, while representatives have 3-year terms). ==Chronological timeline==