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          465        177 
1992          732        297 
1993         1283        478 
1994         1643        604 
1995         2930       1024 
1996         2936       1038 
1997         1801        624 
1998        21531       9161 
1999        12993       5003 
2000        38174      15775 
2001        39063      15169 
2002        30881      13798 
2003        56973      23729 
2004        45741      17567 
2005        80421      24776 
2006       103643      33311 
2007       189532      58678 
2008       109158      31316 
2009        91050      25688 
2010       142789      38392 
2011       153545      42623 
2012       144997      40210 
2013       216988      61871 
2014       555796     141577 
2015       795639     209268 
2016       652436     169474 
2017       548098     148354 
2018       343887      96661 
2019       855891     208824 
2020       603775     153447 
2021       813715     192926 
2022       612412     175320 
2023       552344     158061 
2024       606673     174649 
2025       422860     120904