https://www.planespotters.net/production-list/Boeing/737/737...

The 737-700, -800 and -900ER, the most widespread versions of the previous 737NG,[10] are replaced by the 737 MAX 7, MAX 8 and MAX 9, respectively[61] (FAA type certificate: 737-7, -8, and -9[8]). The 737 MAX 8 entered service in May 2017,[2] and the MAX 9 entered service in March 2018.[62] The MAX 7 is expected to enter service in January 2019, followed by the MAX 200 later in 2019, and the MAX 10 in 2020.