For this we need to know the average amount of sedentary behaviour when it is measured in different ways:
Harvey JA, Chastin SFM, Skelton JA, 2014. How Sedentary are Older People A Systematic Review of the Amount of Sedentary Behavior. Journal of Aging & Physical Activity, 2014 Nov 11. [Epub ahead of print]
To answer this we need to consider the PREVALENCE of sedentary behaviour:
Harvey, Juliet A.; Chastin, Sebastien F.M.; Skelton, Dawn A. 2013. “Prevalence of Sedentary Behavior in Older Adults: A Systematic Review.” Int. J. Environ. Res. Public Health 10, no. 12: 6645-6661.