Table 3: The results of generalized estimating equations assessing the mean densities across three steps over the time.

Parameter	B	95% Confidence Interval		Std. Error
		Lower	Upper		Sig.
(Intercept)	1.988	1.951	2.026	.019	<0.001
Step
3	-.700	-.729	-.672	.014	<0.001
2	-.237	-.267	-.207	.015	<0.001
1	Reference category
time	-.001	-.001	-9*10-4	1*10-4	<0.001
Step 3* time	2*10-4	-8*10-5	.001	2*10-4	.156
Step 2* time	2*10-4	1*10-4	3*10-4	4*10-5	<0.001
Step 1* time	Reference category