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         2216        801 
1995         3357       1167 
1996         3570       1254 
1997         2326        793 
1998        23228       9795 
1999        14498       5559 
2000        40372      16750 
2001        42882      16627 
2002        32387      14479 
2003        60898      25259 
2004        47780      18328 
2005        84569      26009 
2006       109741      35089 
2007       202117      62053 
2008       123272      35106 
2009       100122      28158 
2010       116509      32391 
2011       173747      48073 
2012       161533      44704 
2013       247043      70125 
2014       588235     151117 
2015       713386     189307 
2016       686477     178141 
2017       581548     157390 
2018       385775     108173 
2019       926181     227488 
2020       676302     173164 
2021       888608     212518 
2022       660349     188859 
2023       607320     172986 
2024       269274      78063