i have the numbers on my chart set like this.....

1
2
3
4
5
6
7
0 1 2 3 4

but i want to change it to this.......

7
6
5
4
3
2
1
0 1 2 3 4


how do i flip-flop the y-axis this way. (I need to do this for good reason!)
Please help!