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         2985       1043 
1996         2953       1044 
1997         1819        630 
1998        21582       9184 
1999        13106       5043 
2000        38391      15867 
2001        39228      15235 
2002        30753      13769 
2003        57396      23894 
2004        46057      17680 
2005        80767      24881 
2006       104210      33480 
2007       190677      58989 
2008       110998      31812 
2009        92064      25964 
2010       144162      38746 
2011       155756      43232 
2012       147275      40829 
2013       218776      62363 
2014       562163     143282 
2015       799493     210293 
2016       656243     170501 
2017       551685     149366 
2018       348727      97993 
2019       860358     210030 
2020       612653     155896 
2021       823792     195563 
2022       616296     176421 
2023       555424     158903 
2024       611733     176245 
2025       286736      82528