Histograms of line ratios with ¹²CO for pixels where both the line emission and ¹²CO emission are significantly detected (> 3σ) inside the full FoV (black) and the central 1 kpc (blue) and central 0.4 kpc (in diameter, red). We mark averages (log₁₀(mean(line/CO))) for the full FoV and central apertures (dashed gray, blue, and red line, respectively). The histograms are normalized to have an integrated area of unity.