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        13115       5046 
2000        38393      15868 
2001        39230      15236 
2002        30755      13770 
2003        57409      23899 
2004        46064      17683 
2005        80771      24883 
2006       104216      33482 
2007       190689      58992 
2008       111025      31819 
2009        92064      25964 
2010       144182      38751 
2011       155803      43245 
2012       147289      40833 
2013       218783      62365 
2014       562346     143322 
2015       799507     210283 
2016       656256     170496 
2017       551717     149377 
2018       348765      98004 
2019       860423     210051 
2020       612775     155931 
2021       823900     195594 
2022       616398     176450 
2023       555487     158922 
2024       611902     176283 
2025       286081      82327