Year   APO
1948   2.917
1949   3.944
1950   2.925
1951   2.533
1952   3.285
1953   2.891
1954   2.501
1955   4.056
1956   3.672
1957   1.865
1958   4.624
1959   2.976
1960   3.595
1961   4.354
1962   3.608
1963   2.263
1964   4.125
1965   1.634
1966   1.981
1967   1.565
1968   1.545
1969   1.702
1970   4.093
1971   4.491
1972   1.412
1973   4.205
1974   4.430
1975   5.345
1976   2.084
1977   1.301
1978   1.986
1979   0.258
1980   2.292
1981   2.727
1982   1.111
1983   4.096
1984   2.723
1985   3.332
1986   2.114
1987   2.200
1988   3.187
1989   3.263
1990   2.524
1991   2.266
1992   1.470
1993   1.506
1994   0.527
1995   3.021
1996   2.638
1997  -1.144
1998   4.209
1999   3.687
2000   3.467
2001   3.214
2002   1.874
2003   1.963
2004   1.795
2005   3.027
2006   0.964
2007   3.537
2008   3.094
2009   1.049
2010   4.901
2011   3.462
2012   1.893
2013   3.753
2014   1.740
2015  -0.776
2016   2.742
2017   3.526
2018   0.849
2019   2.652
2020   4.048
2021   4.196