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          492        186 
1992          770        310 
1993         1356        504 
1994         2228        805 
1995         3359       1168 
1996         3570       1254 
1997         2326        793 
1998        23228       9795 
1999        14500       5560 
2000        40381      16754 
2001        42882      16627 
2002        32395      14481 
2003        60903      25260 
2004        47783      18329 
2005        84581      26012 
2006       109757      35094 
2007       202139      62059 
2008       123322      35119 
2009       100152      28166 
2010       116545      32400 
2011       173820      48092 
2012       161580      44717 
2013       247143      70153 
2014       589605     151443 
2015       715375     189794 
2016       688755     178605 
2017       597199     161283 
2018       392298     109940 
2019       926198     227455 
2020       676465     173211 
2021       888801     212571 
2022       660476     188894 
2023       607524     173046 
2024       269378      78093