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         1525        561 
1994         2317        836 
1995         3368       1171 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14520       5567 
2000        40438      16779 
2001        42995      16673 
2002        32451      14505 
2003        61106      25336 
2004        47903      18372 
2005        85151      26182 
2006       110611      35347 
2007       203542      62439 
2008       124767      35518 
2009       101323      28480 
2010       117938      32763 
2011       176622      48845 
2012       164077      45370 
2013       254273      71922 
2014       604378     154746 
2015       729498     193454 
2016       713004     184237 
2017       600731     162061 
2018       395532     110832 
2019       928304     227880 
2020       683436     175070 
2021       892815     213678 
2022       662824     189578 
2023       601668     173234 
2024       241959      70037