Molecular gas fraction (M_H2/(M_H2 + M_HI)) as a function of the average gas phase metallicity (left panel) and the average molecular gas surface density (right panel) in Haro 11 (red star) and other nearby galaxies. The (U)LIRGS sample is marked as blue squares, which is collected from the GOALs survey (Armus et al. 2009; Stierwalt et al. 2013; Shangguan et al. 2019) and cross-matched with the ALFALFA HI survey (Haynes et al. 2018), similar to the data in the right panel of Fig. 7. Black triangles represent normal star forming galaxies with M_* ≥ 10¹⁰ M_⊙ from the Cold GASS survey (Catinella et al. 2010, 2012, 2013). The nearby dwarf irregular or compact galaxies collected from the Little THINGS survey (Hunter et al. 2012, 2019) are shown as purple circles.