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         2204        797 
1995         3357       1167 
1996         3570       1254 
1997         2326        793 
1998        23228       9795 
1999        14498       5559 
2000        40372      16750 
2001        42880      16626 
2002        32387      14479 
2003        60898      25259 
2004        47780      18328 
2005        84557      26005 
2006       109741      35089 
2007       202105      62050 
2008       123259      35103 
2009       100116      28156 
2010       116494      32387 
2011       173709      48063 
2012       161515      44699 
2013       247006      70116 
2014       588161     151098 
2015       713351     189299 
2016       686872     178257 
2017       581455     157368 
2018       384842     107914 
2019       919305     225703 
2020       676186     173131 
2021       888440     212469 
2022       660342     188857 
2023       607250     172973 
2024       269209      78044