As of my last update in January 2022, there are a total of 15 books in the "Diary of a Wimpy Kid" series by Jeff Kinney. The books in the series are:
1. Diary of a Wimpy Kid (2007)
2. Diary of a Wimpy Kid: Rodrick Rules (2008)
3. Diary of a Wimpy Kid: The Last Straw (2009)
4. Diary of a Wimpy Kid: Dog Days (2009)
5. Diary of a Wimpy Kid: The Ugly Truth (2010)
6. Diary of a Wimpy Kid: Cabin Fever (2011)
7. Diary of a Wimpy Kid: The Third Wheel (2012)
8. Diary of a Wimpy Kid: Hard Luck (2013)
9. Diary of a Wimpy Kid: The Long Haul (2014)
10. Diary of a Wimpy Kid: Old School (2015)
11. Diary of a Wimpy Kid: Double Down (2016)
12. Diary of a Wimpy Kid: The Getaway (2017)
13. Diary of a Wimpy Kid: The Meltdown (2018)
14. Diary of a Wimpy Kid: Wrecking Ball (2019)
15. Diary of a Wimpy Kid: The Deep End (2020)
Additionally, there are several supplementary books and spin-offs in the series, including "Diary of a Wimpy Kid: Do-It-Yourself Book," "Diary of a Wimpy Kid: Movie Diary," and "Diary of a Wimpy Kid: Rowley Jefferson's Journal," among others.