Variations in the AGN fraction (in %) with local overdensity (σ_δ) for all different types of AGNs combined at 2 < z < 4. The σ_δ is divided into three different bins – (i) σ_δ < 2.0 (blue): coeval field, (ii) 2.0 < σ_δ < 5.0 (green): intermediate overdensity, (iii) σ_δ > 5 (red): highest overdensity peaks. The figure shows a clear trend of an increasing AGN fraction with the increasing local overdensities of galaxies.