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         2252        813 
1995         3362       1169 
1996         3570       1254 
1997         2326        793 
1998        23228       9795 
1999        14503       5561 
2000        40391      16758 
2001        42932      16646 
2002        32402      14484 
2003        60966      25283 
2004        47812      18339 
2005        84758      26065 
2006       110032      35176 
2007       202656      62202 
2008       123996      35307 
2009       100628      28292 
2010       117138      32555 
2011       175109      48434 
2012       163077      45098 
2013       251160      71073 
2014       596953     152985 
2015       722865     191757 
2016       707621     183135 
2017       597806     161361 
2018       392678     110047 
2019       925884     227288 
2020       680263     174137 
2021       890262     212993 
2022       661032     189046 
2023       616101     174173 
2024       268807      77912