I'm not sure where the 700+ statistic came from, unless you're referring to the Church investigations which were over a [i]supposed[/i] grail, in which case that's inherently different from the Holy Grail War and should not be compared to one another. The reason it's considered a pittance is because it is backwater for an association magus (Japan/Asia in general and all that) and because of the three families involved in its creation, only one is noteworthy to a western magus, and even then they're recluses who barely communicate with anyone. As far at the Fate/Stay Night line is concerned, there have only been 5 Holy Grail Wars in the sense of the grand ritual. 

The Fate/Zero war is the 4th HGW. The only glimpse we have of any war prior to that is in Fate H/A where the characters are forced into the role of the participants of the 3rd HGW. 

Fate/Extra takes place in the Moon Cell, which sort of allows for additional bullshittery because it's essentially a stronger, alien grail. Also on the Moon.