Notes. The areal coverage is determined by the area in which high-cadence observations are being undertaken (Udalski et al. 2015; Sumi 2010; Mainzer et al. 2005; Henderson et al. 2014; Hempel et al. 2014; Penny et al. 2013; Spergel et al. 2015). For ground-based, the efficiency gives the fraction of the yearly rate which is detectable due to the year-round observability of the bulge and weather interruptions. For space-based, the efficiency indicates the total baseline of proposed exoplanet survey, expressed as a fraction of a year.