Regional totals;Period;Total
National Total;2024;21.99
National Total;2023;22.51
National Total;2022;22.95
National Total;2021;23.34
National Total;2020;23.78
National Total;2019;24.14
National Total;2018;24.39
National Total;2017;24.50
National Total;2016;24.58
National Total;2015;24.57
National Total;2014;24.44
National Total;2013;24.27
National Total;2012;24.06
National Total;2011;23.80
National Total;2010;23.50
National Total;2009;23.24
National Total;2008;22.98
National Total;2007;22.90
National Total;2006;22.84
National Total;2005;22.79
National Total;2004;22.95
National Total;2003;23.01
National Total;2002;23.15
National Total;2001;23.37
National Total;2000;23.72
National Total;1999;24.20
National Total;1998;24.87
National Total;1997;25.64
National Total;1996;26.58
National Total;1995;27.62
National Total;1994;28.83
National Total;1993;30.02
National Total;1992;31.32
National Total;1991;32.66
National Total;1990;34.06
National Total;1989;35.37
National Total;1988;36.68
National Total;1987;37.91
National Total;1986;39.11
National Total;1985;40.24
National Total;1984;41.40
National Total;1983;42.63
National Total;1982;43.85
National Total;1981;44.90
National Total;1980;45.96
National Total;1979;46.75
National Total;1978;47.26
National Total;1977;47.57
National Total;1976;47.88
National Total;1975;48.07