"Sixteen of the 17 warmest years in the 136-year record all have occurred since 2001, with the exception of 1998. The year 2016 ranks as the warmest on record. (Source: NASA/GISS)."

Additional sources:
https://climate.nasa.gov/vital-signs/global-temperature/

https://earthobservatory.nasa.gov/Features/WorldOfChange/decadaltemp.php