Do Google results make sense?

I did a Google digging research and became puzzled:
I searched for a few Buzz Words and then repeated the search with a combination of them.
The number of entries returned is not in accordance with the known laws of arithmetics!

"Grid Computing" 171,000 entries
where "XXX YYY" means with the exact phrase XXX YYY!
virtualization 1,530,000 entries
"Grid Computing" Virtualization 1,300,000 entries
where space between the terms means with all of the words.
virtualization -"grid computing" 2,580,000 entries
where "-" means exclude the term from the search
-virtualization "grid computing" 4,510,000 entries

In order to verify this mystery I repeated the test with two other terms:

Israel 26,600,000 entries
Jerusalem 4,190,000 entries
Jerusalem Israel 1,120,000 entries
jerusalem -israel 2,150,000 entries
-jerusalem israel 45,300,000 entries

To my understanding the situation can be demonstrated as in the following plot:




Does this mean we should make a compromise in East Jerusalem's territory
(have less Jerusalem and get more Israel) ???


Comments are welcome to shed light on this mystery

Note: If you want to reproduce my test take into account:
1. There may be a small change in the number of entries found. This fluctuation is however negligible.
2. There is another small difference in the number of entries if you try capital letters instead of small letters or change the order of the words.
3. Drawing was produced using the free tool Dia.