[Homer]

P(1 flip) = 1/2
P(2) = 1/4
P(3) = 1/8
...
P(9) = 1/512

P(1) + P(2) + ... + P(9) = P(1-9) = .998046875

P(10 or more) = 1 - P(1-9) = .001953 (or 1/512)

So it happens about .713 times per year, or around twice every three years.

Is this the answer or am I missing something??

-- Homer