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          444        170 
1992          721        293 
1993         1283        478 
1994         1631        600 
1995         2897       1013 
1996         2895       1024 
1997         1787        619 
1998        21450       9127 
1999        12872       4961 
2000        37982      15686 
2001        39312      15237 
2002        34023      14823 
2003        56216      23432 
2004        45317      17412 
2005        79827      24598 
2006       102805      33065 
2007       187371      58100 
2008       106198      30522 
2009        89095      25168 
2010       141259      37994 
2011       150337      41755 
2012       141313      39209 
2013       214512      61170 
2014       545506     138859 
2015       794596     209106 
2016       644618     167367 
2017       543329     147058 
2018       337684      94944 
2019       848846     207247 
2020       590459     149765 
2021       801550     189593 
2022       607232     173827 
2023       546808     156480 
2024       605235     173881 
2025       507946     144816