A marketing staff in a bank is collecting data on its customers. The following is part of the dataset obtained.

Customer ID	Gender	Suburb	Age	Employment status	Weekly salary	Number of Accounts	Years of banking
001	Female	Sydney	44	Part-time	Less than 500	2	3
002	Male	Homebush	55	Full-time	500 to less than 1000	3	10
003	Male	Randwick	40	Unemployed	Less than 500	1	12
004	Female	Glebe	33	Full-time	1000 to less than 1500	2	5
005	Female	Darlington	40	Part-time	500 to less than 1000	1	1

Calculate the sample mean age of the customer.