It might be every 10 years.
Every 4 years.
every 4 years
Leap years occur every 4 years.
Every four years.
About every 2 years.
each census is taken every 10 years
every 2 years
Every three years
30
100 every 2 years.
2 years after every winter olympics.
9.6718 x 1083 (rounded)BTW . . . "Google" is not a number. "Googol" is.