How many field combinations played?

[Hitchhiker 42]

Based on rough calculations, there have been 121 events as of the end of week 6. Each event features about 100 matches (80-ish quals, the rest in elims). Total, that is 12100 matches. According to above, about 90% (here: FRC Blog) different field combinations have been played at each event (out of number of matches). That'd make up 10890 combinations (probably some repetition, but this is a rough estimate). Out of 18432 possible combinations. Total, that makes up 59% played combinations (in reality, less due to many combinations being played over and over and different events). So 59% is a high estimate.

A low estimate would assume the 90% different fields at each event were the same combination. So that'd be about 90 different combinations or 0.49%.

Is there a way to get a better estimate than 0.49%-59%?