Fluctuation properties of the unfolded eigenfrequencies of the microwave billiard containing one disk: (a) the average over the nearest neighbor spacing distribution P(s), (b) the cumulative nearest-neighbor spacing distribution I(s), (c) the number variance Σ 2 ( L ) , and (d) the Dyson–Mehta statistics Δ 3 ( L ) for the different measurments listed in Table 1. The solid, dashed, and dash-dotted black lines show the curves for Poisson, GOE, and semi-Poisson statistics, respectively. The red histograms and diamonds show the curves deduced from the measurements.