Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          468        178 
1992          740        300 
1993         1296        483 
1994         1666        612 
1995         3006       1050 
1996         2959       1046 
1997         1828        633 
1998        21610       9194 
1999        13245       5091 
2000        38509      15921 
2001        39309      15270 
2002        33169      14586 
2003        57598      23974 
2004        46199      17733 
2005        81079      24974 
2006       104600      33595 
2007       191266      59147 
2008       111810      32028 
2009        92584      26108 
2010       144989      38953 
2011       157045      43581 
2012       148416      41136 
2013       220164      62744 
2014       564867     143938 
2015       798537     210221 
2016       657880     170973 
2017       554201     150018 
2018       350750      98548 
2019       862784     210626 
2020       616172     156825 
2021       828927     196817 
2022       619062     177212 
2023       558169     159678 
2024       616953     177790 
2025       219863      62837