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        12866       4958 
2000        37964      15678 
2001        39296      15230 
2002        33704      14716 
2003        56563      23546 
2004        45286      17401 
2005        79815      24594 
2006       102767      33052 
2007       187283      58077 
2008       106039      30478 
2009        88943      25127 
2010       141203      37979 
2011       150097      41690 
2012       141015      39127 
2013       214362      61130 
2014       544955     138706 
2015       794908     209197 
2016       644689     167376 
2017       542800     146947 
2018       337257      94827 
2019       848397     207126 
2020       589847     149593 
2021       800897     189431 
2022       606831     173714 
2023       546637     156429 
2024       605051     173829 
2025       511217     145894