pre_text: 5. Operating Expenses Notes: (1) Includes equipment costs related to ICT services. (2) Includes supplies and services, as well as rentals of properties and mobile base stations.
table: Group
table: 2019 2018
table: S$ Mil S$ Mil
table: Cost of equipment sold (1) 3,106.1 2,696.7
table: Other cost of sales 2,767.1 2,499.2
table: Staff costs 2,597.3 2,760.1
table: Selling and administrative costs (2) 2,472.6 2,536.6
table: Traffic expenses 1,573.4 1,615.8
table: Repair and maintenance 388.0 367.9
table: 12,904.5 12,476.3
question: Analyse this data from a financial earnings document. What is the average of the top 3 operating expenses subcategories in 2019?