Ratio of L_{CI1 − 0} to L_{CO(4 − 3)} as a function of the cooling budget through [CI] 1–0. The red stars are the GEMS. Blue, green, and orange dots indicate the samples of low-redshift star-forming galaxies from Kamenetzky et al. (2016), and the high-redshift samples of gravitationally lensed sources from the SPT (Bothwell et al. 2017) and the submillimeter galaxies of Alaghband-Zadeh et al. (2013), respectively. The blue line shows the average relationship derived from the comparison samples. The blue hatched region shows a range of a factor of ±2 around this average. The typical measurement uncertainty is shown in the lower-right corner.