[EricH]

Missed at least one: 2009 had gray carpet. Admittedly, it's easy to miss, but the border of the field--1' or so, as I recall--was gray carpet (this to enable escaping from pins); the carpet was laid out and then the FRP was unrolled on top and secured.

"Ground pepper" is in fact a shade of gray.

Non-gray-carpet fields:
1992, corn kernels
1993 (Rug Rage)--not sure offhand, but almost certainly carpet. Gray or not, not entirely certain.
2010, green carpet (soccer field)
2012, tan carpet (basketball court)

1997 I'm pretty sure was gray carpet.
2000 was DEFINITELY gray carpet.

So, in 24 games, only 3-5 did NOT have gray carpet as the primary surface. 80% or so.

And, just to stir the pot, there has already been a water game. One of the games I listed in this post had water in the game. Anybody want to take a guess?