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          936        367 
1993         1663        608 
1994         2323        838 
1995         3371       1172 
1996         3576       1256 
1997         2329        794 
1998        23258       9806 
1999        14524       5569 
2000        40467      16792 
2001        43046      16691 
2002        32478      14518 
2003        61200      25371 
2004        47953      18391 
2005        85323      26235 
2006       110793      35402 
2007       203953      62550 
2008       125117      35612 
2009       101752      28595 
2010       118256      32847 
2011       177358      49049 
2012       164694      45520 
2013       255852      72295 
2014       606830     155139 
2015       731979     193973 
2016       640851     167277 
2017       602864     162407 
2018       396637     111014 
2019       931320     228303 
2020       685884     175723 
2021       894379     214085 
2022       664039     189938 
2023       603105     173657 
2024       220547      63746