Hi all you mathematicians?

Can you give me an answer to this question, not just how to work it out but a result. I do the lottery every week, the lottery has 49 numbers of which to choose from, 7 numbers are drawn every week, I have chosen 18 numbers all different. What are the odds of not matching any of my 18 numbers against the 7 drawn out of 49, not just once but more than 10 times. I think I must be the unluckiest person alive.