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          492        186 
1992          895        353 
1993         1663        608 
1994         2320        837 
1995         3368       1171 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14522       5568 
2000        40454      16786 
2001        43018      16681 
2002        32466      14512 
2003        61178      25363 
2004        47946      18389 
2005        85268      26217 
2006       110754      35389 
2007       203812      62512 
2008       125014      35584 
2009       101662      28572 
2010       118172      32825 
2011       177159      48993 
2012       164481      45478 
2013       255258      72199 
2014       605216     154956 
2015       730761     193789 
2016       696327     179984 
2017       601367     162183 
2018       395645     110848 
2019       930665     228164 
2020       685257     175572 
2021       894177     214019 
2022       663784     189854 
2023       602893     173584 
2024       243729      70573