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         1669        610 
1994         2333        842 
1995         4430       1529 
1996         3602       1265 
1997         2340        798 
1998        23334       9837 
1999        14618       5609 
2000        40751      16923 
2001        41820      16315 
2002        32971      14725 
2003        62030      25710 
2004        48707      18689 
2005        87078      26744 
2006       112782      35987 
2007       207796      63602 
2008       128753      36586 
2009       104657      29384 
2010       121647      33742 
2011       183313      50677 
2012       169899      46998 
2013       265081      75168 
2014       661100     168567 
2015       773338     204892 
2016       577568     154236 
2017       587195     157659 
2018       406795     114118 
2019       926963     226297 
2020       712986     183009 
2021       971881     232098 
2022       692839     198080 
2023       629864     181241 
2024        83637      24372