Table 2.

Frequency of ETCO₂ use

	Frequency of ETCO2 use
Year	ETCO2 use		Untreated group
	NO.	%	NO.	%
2005	7	1.32	522	98.68
2006	2	0.35	571	99.65
2007	5	0.86	574	99.14
2008	7	1.04	666	98.96
2009	0	0	643	100
2010	7	1.07	646	98.93
2011	14	2.03	675	97.97
2012	41	5.84	661	94.16