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         2225        804 
1995         3359       1168 
1996         3570       1254 
1997         2326        793 
1998        23228       9795 
1999        14500       5560 
2000        40381      16754 
2001        42882      16627 
2002        32390      14480 
2003        60898      25259 
2004        47783      18329 
2005        84577      26011 
2006       109745      35090 
2007       202135      62058 
2008       123322      35119 
2009       100148      28165 
2010       116540      32399 
2011       173809      48089 
2012       161566      44713 
2013       247118      70146 
2014       589598     151441 
2015       715342     189785 
2016       686620     178154 
2017       591743     160077 
2018       392277     109934 
2019       926110     227466 
2020       676436     173201 
2021       888726     212549 
2022       660421     188880 
2023       607451     173025 
2024       269333      78080