2G is still the most common deployed mobile access technology. It is hard to believe but as per my discussions with probably more than twenty Mobile Operators, 2G , especially GSM is the most common mobile access technology.
Almost all those twenty Mobile operators deployed 3G and LTE and some of them deployed LTE Advanced as well, their common feedback ; as the developing and undeveloped continents have huge human population and they have legacy infrastructure, they have 2G mobile networks, thus worldwide, 2G is most common mobile network architecture as of 2017.
In fact, below research supports this claim.
In the above picture, HSPA (High speed packet access) is the enhanced version of 3G and LTE is considered as 4G technology. CDMA (Code Division Multiple Access) is also an enhanced 3G technology.
Though analog 1G is not used by anyone and 2G networks are slowly removed and lose the market share, just for your info, it is still the most common mobile technology worldwide.