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          532        200 
1992          936        367 
1993         1672        611 
1994         2339        844 
1995         4430       1529 
1996         3605       1266 
1997         2337        797 
1998        23345       9841 
1999        14646       5620 
2000        40829      16957 
2001        41928      16362 
2002        33163      14800 
2003        62273      25812 
2004        48889      18762 
2005        87553      26875 
2006       113388      36168 
2007       208495      63794 
2008       129764      36862 
2009       105355      29575 
2010       122436      33950 
2011       184761      51065 
2012       171081      47323 
2013       267315      75790 
2014       665805     169777 
2015       778277     206215 
2016       575106     153977 
2017       554631     152248 
2018       407758     114416 
2019       924681     225833 
2020       717127     184117 
2021       928893     223502 
2022       692514     198111 
2023       638923     183844 
2024        16929       5269