Annually
twice-a-day or it can be called semi-diurnal which relates to such occurrences as tides.
Usually those days are called holidays.
yes i'm positive it happens every year
Winter happens every year in December
weekly
It happens every year
Leap year. It happens in February. february, and it occurs on leap years
A leap year happens every 4 years, where February has 29 days instead of the normal 28.
Every year is an important year. It depends on what happens in it
Happens every year. (Perennial)
Annual.
Every three months is called a quarter. And there are four quarters in a year.