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          468        178 
1992          735        298 
1993         1283        478 
1994         1655        608 
1995         2945       1029 
1996         2941       1040 
1997         1810        627 
1998        21554       9171 
1999        13056       5025 
2000        38233      15799 
2001        39134      15197 
2002        30572      13698 
2003        57147      23796 
2004        45835      17598 
2005        80538      24811 
2006       103859      33375 
2007       189941      58789 
2008       109885      31513 
2009        91456      25798 
2010       143223      38506 
2011       154307      42834 
2012       145710      40405 
2013       217554      62022 
2014       558101     142208 
2015       797507     209764 
2016       654398     170008 
2017       549351     148703 
2018       345499      97099 
2019       857778     209310 
2020       607032     154358 
2021       816861     193780 
2022       613450     175613 
2023       553348     158345 
2024       607767     174991 
2025       362026     104167