Actually I did mean an inherit thing, but I guess a select and righ-click lock thing would do too.
For your information, this is how my trees with charts look like:
Top 40
--> 60's
--> --> 1965
--> --> --> Week 1
--> --> --> Week 2
etc.
--> --> 1966
-->-->--> Week 1
--> 70's
-->-->1971
-->---> ---> Week 1
-->---> ---> Week 2
So you (might) see that selecting and locking gets reduced to 45 years (means 45 times). Still a lot of work, but far better than 2000 times.
However, if you bump into some code that makes inheriting possible, you'll be my man of 2011! :-)