Year	% Contributors/a	% Coverage /b
Year	% Contributors/a	Total	Up to 14 years	60 - 64 years	65 years or more
1984	35.88	68.00	60.03	86.20	90.20
1988	40.76	69.66	63.42	87.78	91.78
1992	41.91	79.53	76.22	93.01	95.23
1996	37.99	77.25	72.18	94.60	95.84
2001	37.06	68.92	60.29	93.32	95.65
2002	37.15	76.24	70.24	95.00	96.68
2003	37.80	66.73	56.16	93.51	96.22
2004	38.15	65.80	54.92	92.60	95.42
2005	39.53	67.04	56.14	93.03	95.43
2006	40.96	67.86	57.12	91.61	93.76
2007	41.89	68.56	57.49	91.86	93.87
2008	43.74	69.93	58.04	92.54	94.62
2009	44.55	70.36	58.49	92.57	94.52
2011	46.89	71.90	59.57	92.50	94.41
Var. 2011/1984	30.68	5.74	−0.76	7.31	4.66