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         1280        477 
1994         1631        600 
1995         2897       1013 
1996         2895       1024 
1997         1784        618 
1998        21448       9126 
1999        12863       4957 
2000        37960      15676 
2001        39112      15166 
2002        35428      15298 
2003        57956      24010 
2004        45260      17392 
2005        79815      24594 
2006       102763      33051 
2007       187257      58070 
2008       105982      30464 
2009        88913      25119 
2010       141173      37971 
2011       150057      41679 
2012       140916      39101 
2013       214342      61124 
2014       544815     138668 
2015       796118     209528 
2016       645087     167487 
2017       542878     146993 
2018       337226      94817 
2019       848564     207181 
2020       590054     149660 
2021       800716     189381 
2022       606733     173687 
2023       546595     156417 
2024       604521     173695 
2025       522594     148975