Introduction 1A: 13.75 G — 1636 1B: 1637 — 1809 2A: circa 1810 — 1857 2B: 1858 — 1884 3A: 1885 — 1902 3B: 1903 — 1924 4A: 1925 — 1936 4B: 1937 — 1947 5A: circa 1948 — 1956 5B: 1957 — 1963 6A: 1964 — 1970 6B: 1979 — 1979 7A: 1980 — 1991 7B: 1992 — 2022