| 年份 | 乍得 |
|---|---|
| 2023 | - |
| 2022 | 4.29386 |
| 2021 | 4.26746 |
| 2020 | 4.19049 |
| 2019 | 4.24412 |
| 2018 | 4.25364 |
| 2017 | 4.11957 |
| 2016 | 3.8656 |
| 2015 | 3.82127 |
| 2014 | 4.12579 |
| 2013 | 4.03461 |
| 2012 | 3.88585 |
| 2011 | 3.80779 |
| 2010 | 3.64074 |
| 2009 | 3.66915 |
| 2008 | 3.59665 |
| 2007 | 3.5428 |
| 2006 | 3.69201 |
| 2005 | 4.14326 |
| 2004 | 4.58773 |
| 2003 | 4.12253 |
| 2002 | 3.5957 |
| 2001 | 3.48252 |
| 2000 | 3.56712 |
| 1999 | 3.63003 |
| 1998 | 3.56031 |
| 1997 | 3.56963 |
| 1996 | 4.57523 |
| 1995 | 4.54347 |
| 1994 | 2.36884 |
| 1993 | 3.09138 |
| 1992 | 5.22412 |
| 1991 | 4.64277 |
| 1990 | 3.7309 |
| 1989 | 4.37862 |
| 1988 | 4.39939 |
| 1987 | 4.52294 |
| 1986 | 4.0121 |
| 1985 | 1.97284 |
| 1984 | 2.28724 |
| 1983 | 6.01327 |
| 1982 | 5.76324 |
| 1981 | 1.05518 |
| 1980 | 1.16338 |
| 1979 | 3.09091 |
| 1978 | 7.26566 |
| 1977 | 7.36506 |
| 1976 | 7.55945 |
| 1975 | 7.76402 |
| 1974 | 7.96811 |
| 1973 | 8.08592 |
| 1972 | 8.35949 |
| 1971 | 8.26944 |
| 1970 | 8.2868 |
| 1969 | 8.24791 |
| 1968 | 8.26198 |
| 1967 | 8.27123 |
| 1966 | 8.32234 |
| 1965 | 8.40398 |
| 1964 | 6.49215 |
| 1963 | 5.85336 |
| 1962 | 5.84454 |
| 1961 | 5.83887 |
| 1960 | - |