*3.1. Survey Responses*

A total of 4784 responses were collected in 2010 (*n* = 1512; response rate: 47.4%), 2013 (*n* = 1352; response rate: 42.1%), and 2016 (*n* = 1920; response rate: 38.6%). A total of 4784 responses were collected in 2010 (*n* = 1512; response rate: 47.4%), 2013 (*n* = 1352; response rate: 42.1%), and 2016 (*n* = 1920; response rate: 38.6%). Overall, small and medium worksites were less likely to respond to the survey (response rate 39.2% and 36.3%, respectively) than large worksites (response rate: 47.3%). Over the three study periods, response rates were consistent among medium size worksites but increased among large and small worksites (*p* < 0.0001). The response rate decreased among large worksites from 54.5% in 2010 to 38.1% in 2016. Among small worksites, the response rate decreased from 43.4% in 2010 to 31.0% in 2016 (Table S2).

Table 1 presents the characteristics of participating worksites by size and industry sector grouping over the three study periods (2010, 2013, and 2016). Small (10–49 employees) and medium (50–199 employees) worksites comprised more than three-quarters of the respondents across the years. Specifically, in 2010, the majority (46%) of respondents were medium size worksites, whereas as in 2013 and 2016, the majority of respondents were small worksites (43.1% and 45.9%, respectively). Worksites in the 'Health Care and Social Assistance' industry sector were the most represented sector in all survey years (17–20%), followed by 'Wholesale and Retail Trade' (14–16%) and 'Information, Finance, and Management Services' (13–14%).
