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         1862        680 
1995         3324       1156 
1996         3559       1250 
1997         2312        789 
1998        23170       9773 
1999        14473       5549 
2000        40121      16638 
2001        40968      15966 
2002        32088      14354 
2003        60236      25004 
2004        47516      18226 
2005        83677      25741 
2006       108158      34630 
2007       198966      61214 
2008       120372      34321 
2009        98654      27758 
2010       113916      31708 
2011       168942      46774 
2012       158729      43932 
2013       237761      67601 
2014       580708     149150 
2015       702636     186340 
2016       676733     175717 
2017       575951     155745 
2018       375812     105411 
2019       901959     220617 
2020       651709     166296 
2021       870447     207529 
2022       645160     184711 
2023       592273     169521 
2024       378688     110053