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         1658        609 
1995         2991       1045 
1996         2953       1044 
1997         1822        631 
1998        21587       9186 
1999        13132       5052 
2000        38411      15877 
2001        39244      15242 
2002        30773      13778 
2003        57441      23912 
2004        46082      17690 
2005        80808      24894 
2006       104259      33494 
2007       190782      59017 
2008       111098      31839 
2009        92135      25985 
2010       144261      38771 
2011       155998      43298 
2012       147434      40871 
2013       219001      62428 
2014       562616     143394 
2015       799060     210210 
2016       656114     170491 
2017       551874     149423 
2018       349078      98091 
2019       860750     210123 
2020       613363     156086 
2021       824477     195712 
2022       616817     176567 
2023       555880     159027 
2024       612561     176466 
2025       286818      82540