I've been searching through but no luck finding what I need.

I have data files with over 8000 rows of data, I don't need all the data. I want to keep every 10th row begining with row 9. Rows 1 through 8 have header information.

1.header info
2.header info
3.header info
4.header info
5.header info
6.header info
7.header info
8.header info
9.keep data
10.delete
11.delete
12.delete
13.delete
14.delete
15.delete
16.delete
17.delete
18.delete
19.keep data
20.delete
21.delete
22.delete
23.delete
24.delete
25.delete
26.delete
27.delete
28.delete
29.keep data
30.delete
and so on