Table 5. Variation in the density estimate between years (results of the zero inflated Generalized Linear Model with a negative binomial error structure and log link function).

Count model (with 2011 in the intercept)
	Estimate	Std. Error	z value	P value
Intercept	1.172	0.311	3.763	<0.001
Year 2012	−0.685	0.349	−1.958	0.050
Year 2013	0.038	0.354	0.109	0.913
Ac.term	0.467	0.146	3.181	0.001

‘Year’ was dummy coded. The intercept represents 2011 in the first table and 2012 in the second table.