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         2219        802 
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        84573      26010 
2006       109741      35089 
2007       202121      62054 
2008       123288      35110 
2009       100129      28160 
2010       116513      32392 
2011       173774      48080 
2012       161550      44709 
2013       247074      70134 
2014       589539     151424 
2015       715287     189769 
2016       686500     178133 
2017       581382     157344 
2018       391480     109709 
2019       926112     227472 
2020       676299     173163 
2021       888650     212530 
2022       660368     188865 
2023       607365     172999 
2024       269284      78066