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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4369       1508 
1996         3593       1262 
1997         2334        796 
1998        23312       9827 
1999        14583       5594 
2000        40643      16874 
2001        41651      16244 
2002        32778      14648 
2003        61711      25577 
2004        48484      18601 
2005        86563      26593 
2006       112068      35779 
2007       206663      63294 
2008       127570      36268 
2009       103839      29160 
2010       120488      33433 
2011       181409      50157 
2012       168444      46600 
2013       261997      74304 
2014       648854     165473 
2015       756807     200796 
2016       579448     154574 
2017       610536     163058 
2018       407290     114144 
2019       931751     227180 
2020       702245     180360 
2021       911252     218723 
2022       680447     194623 
2023       618060     177886 
2024       138190      39602