~100 years, ~4 generations

25 years of weak men

25 years of bad times

25 years of strong men

25 years of good times

World reserve currency periods:

- Egypt (3150 BC-1200 BC)

- Lydia (1200BC-550BC)

- Achaemenid Empire (550BC-330BC)

- Macedonia (330BC-315BC)

- Seleucid Empire (315BC - 200BC)

- Rome (200 BC-395 AD)

- Byzantine Empire (395-660 & 750-1200)

- Umayyad Caliphate (660-750)

- Florence & Venice (1200-1450)

- Portugal (1450–1530)

- Spain (1530–1640)

- Netherlands (1640–1720)

- France (1720–1815)

- Great Britain (1815–1944)

- United States (1944-?)