There is no set number, because new comets are discovered all the time. Not all comets that are discovered will be visible with the naked eye.
Comets - 1919 was released on: USA: 30 March 1919
AS is seen most commonly in males 30 years old and older
Bailey's Comets - 1973 - 1.4 was released on: USA: 30 September 1973
30 years = 946,707,779 seconds.
There are 15,724,800 minutes in 30 years.
hmm.. i wonder you idiot. 30 years was the 30 YEARS WAR.. you dumb idiot.
21 years.
2 Years can fit in 30 months.
4006
30
30 months = 2 1/2 years
30 years