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          737        299 
1993         1288        480 
1994         1655        608 
1995         2961       1035 
1996         2950       1043 
1997         1813        628 
1998        21568       9178 
1999        13079       5034 
2000        38313      15832 
2001        39186      15216 
2002        30695      13744 
2003        57271      23845 
2004        45941      17636 
2005        80639      24842 
2006       104004      33419 
2007       190328      58893 
2008       110403      31651 
2009        91719      25869 
2010       143616      38606 
2011       154933      43007 
2012       146600      40648 
2013       218059      62164 
2014       560175     142768 
2015       799092     210204 
2016       655776     170389 
2017       550717     149043 
2018       346834      97466 
2019       859095     209656 
2020       609897     155121 
2021       819979     194546 
2022       614806     175998 
2023       554207     158565 
2024       608945     175453 
2025       339576      97411