The feud between the Montagues and the Capulets is the cause of Romeo and Juliet's deaths, and probably their romance as well. If there were no feud, the two families would have moved in the same circles, and Romeo and Juliet would have known each other all their lives.
I would say that it hasn't increased 20% because 1. if the starting percentage was 18%, you would see a larger precentage but that isn't the case.
Answer:
1. could
2. should
3. can
4. could
5. might
6. can
7. must
8. manage
9. might
10. could
11. should
12. should
13. might
14. must / ought to
These are only suggested others are suitable for some too, I just think these make more sense.
Hope this helps :)